// dottle bot
#ifndef ONLINE_JUDGE
#define DEBUG
#endif
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <queue>
#include <vector>
#include <bitset>
#include <map>
#include <assert.h>
#include <math.h>
#include <set>
#include <random>

#define int long long
const int mod=998244353;
struct modint{
	int x;
	modint(int o=0){x=o;}
	modint &operator = (int o){return x=o,*this;}
	modint &operator +=(modint o){return x=x+o.x>=mod?x+o.x-mod:x+o.x,*this;}
	modint &operator -=(modint o){return x=x-o.x<0?x-o.x+mod:x-o.x,*this;}
	modint &operator *=(modint o){return x=1ll*x*o.x%mod,*this;}
	modint &operator ^=(int b){
		modint a=*this,c=1;
		for(;b;b>>=1,a*=a)if(b&1)c*=a;
		return x=c.x,*this;
	}
	modint &operator /=(modint o){return *this *=o^=mod-2;}
	friend modint operator +(modint a,modint b){return a+=b;}
	friend modint operator -(modint a,modint b){return a-=b;}
	friend modint operator *(modint a,modint b){return a*=b;}
	friend modint operator /(modint a,modint b){return a/=b;}
	friend modint operator ^(modint a,int b){return a^=b;}
	friend bool operator ==(modint a,int b){return a.x==b;}
	friend bool operator ==(modint a,modint b){return a.x==b.x;}
	friend bool operator !=(modint a,int b){return a.x!=b;}
	bool operator ! () {return !x;}
	modint operator - () {return x?mod-x:0;}
	bool operator <(const modint&b)const{return x<b.x;}
};
std::mt19937_64 rnd(586666);
#define nln puts("")
#define od(x) printf("%d",x)
#define odb(x) printf("%d ",x)
#define odl(x) printf("%d\n",x)
#define odp(x,y) printf("%d %d\n",x,y)
#define ol(x) puts("")
#define old(x) printf("%lld",x)
#define oldb(x) printf("%lld ",x)
#define oldl(x) printf("%lld\n",x)
#define oldp(x,y) printf("%lld %lld\n",x,y)
#define rg(x) for(int i=1;i<=(x);i++){
#define rg_(i,x) for(int i=1;i<=(x);i++){
#define fe(u) for(int i=h[u];i;i=e[i].nxt){int v=e[i].v;
#define gr }
#define rrg(x) for(int i=0;i<(x);i++){
#define rdln(a) a[i]=read();
#define rdln0(a,x) rrg(x) rdln(a) gr
#define rdln1(a,x) rg(x) rdln(a) gr

#ifdef int 
#define inf 0x3f3f3f3f3f3f3f3fll
#else 
#define inf 0x3f3f3f3f
#endif
inline int min(int a,int b){return a>b?b:a;}
inline int max(int a,int b){return a<b?b:a;}
#define cmlSEGMIN
#define cmlSEGMAX
#define cmlSEGSUM
class SegTreeAl{
#ifdef cmlSEGMIN
	int minn[1000005<<2];
#endif
#ifdef cmlSEGMAX
	int maxn[1000005<<2];
#endif
#ifdef cmlSEGSUM
	int sum[1000005<<2];
#endif
	int tag[1000005<<2];
#ifdef cmlSEGSUM
	void pushdown(int o,int l,int r)
#else 
	void pushdown(int o)
#endif
	{
		int&t=tag[o];
#ifdef cmlSEGMIN
		minn[o<<1]+=t;
		minn[o<<1|1]+=t;
#endif
#ifdef cmlSEGMAX
		maxn[o<<1]+=t;
		maxn[o<<1|1]+=t;
#endif
#ifdef cmlSEGSUM
		int m=l+r>>1;
		sum[o<<1]+=t*(m-l+1);
		sum[o<<1|1]+=t*(r-m);
#endif
		tag[o<<1]+=t;
		tag[o<<1|1]+=t;
		t=0;
	}
	void add(int o,int l,int r,int L,int R,int v)
	{
		if(L<=l&&r<=R)
		{
#ifdef cmlSEGMAX
			maxn[o]+=v;
#endif
#ifdef cmlSEGMIN
			minn[o]+=v;
#endif
#ifdef cmlSEGSUM
			sum[o]+=v*(r-l+1);
#endif
			tag[o]+=v;
			return;
		}
		int m=l+r>>1;
#ifdef cmlSEGSUM
		pushdown(o,l,r);
#else
		pushdown(o);
#endif
		if(L<=m)add(o<<1,l,m,L,R,v);
		if(m<R)add(o<<1|1,m+1,r,L,R,v);
#ifdef cmlSEGMAX
		maxn[o]=max(maxn[o<<1],maxn[o<<1|1]);
#endif
#ifdef cmlSEGMIN
		minn[o]=min(minn[o<<1],minn[o<<1|1]);
#endif
#ifdef cmlSEGSUM
		sum[o]=sum[o<<1]+sum[o<<1|1];
#endif
	}
#ifdef cmlSEGMIN
	int qmin(int o,int l,int r,int L,int R)
	{
		if(L<=l&&r<=R)
		{
			return minn[o];
		}
		int m=l+r>>1,res=inf;
#ifdef cmlSEGSUM
		pushdown(o,l,r);
#else
		pushdown(o);
#endif
		if(L<=m)res=min(res,qmin(o<<1,l,m,L,R));
		if(m<R)res=min(res,qmin(o<<1|1,m+1,r,L,R));
#ifdef cmlSEGMAX
		maxn[o]=max(maxn[o<<1],maxn[o<<1|1]);
#endif
#ifdef cmlSEGMIN
		minn[o]=min(minn[o<<1],minn[o<<1|1]);
#endif
#ifdef cmlSEGSUM
		sum[o]=sum[o<<1]+sum[o<<1|1];
#endif
		return res;
	}
#endif

#ifdef cmlSEGMAX
	int qmax(int o,int l,int r,int L,int R)
	{
		if(L<=l&&r<=R)
		{
			return maxn[o];
		}
		int m=l+r>>1,res=-inf;
#ifdef cmlSEGSUM
		pushdown(o,l,r);
#else
		pushdown(o);
#endif
		if(L<=m)res=max(res,qmax(o<<1,l,m,L,R));
		if(m<R)res=max(res,qmax(o<<1|1,m+1,r,L,R));
#ifdef cmlSEGMAX
		maxn[o]=max(maxn[o<<1],maxn[o<<1|1]);
#endif
#ifdef cmlSEGMIN
		minn[o]=min(minn[o<<1],minn[o<<1|1]);
#endif
#ifdef cmlSEGSUM
		sum[o]=sum[o<<1]+sum[o<<1|1];
#endif
		return res;
	}
#endif

#ifdef cmlSEGSUM
	int qsum(int o,int l,int r,int L,int R)
	{
		if(L<=l&&r<=R)
		{
			return sum[o];
		}
		int m=l+r>>1,res=0;
#ifdef cmlSEGSUM
		pushdown(o,l,r);
#else
		pushdown(o);
#endif
		if(L<=m)res+=qsum(o<<1,l,m,L,R);
		if(m<R)res+=qsum(o<<1|1,m+1,r,L,R);
#ifdef cmlSEGMAX
		maxn[o]=max(maxn[o<<1],maxn[o<<1|1]);
#endif
#ifdef cmlSEGMIN
		minn[o]=min(minn[o<<1],minn[o<<1|1]);
#endif
#ifdef cmlSEGSUM
		sum[o]=sum[o<<1]+sum[o<<1|1];
#endif
		return res;
	}
#endif
};
#define newe(n) struct Edge{int v;modint w;int nxt;}e[2*n+5];\
typedef int arr[n+5];\
arr h;\
int cnt=1;\
inline void addedge(int u,int v,modint w){e[cnt]=(Edge){v,w,h[u]};h[u]=cnt++;}\
struct node{\
	int u,d;\
	bool operator<(const node&b)const{return d>b.d;}\
};
#define mgs int fa[1<<22],sz[1<<22];\
inline int f(int x){return x==fa[x]?x:fa[x]=f(fa[x]);}\
inline int uf(int x,int y)\
{\
    int fx=f(x),fy=f(y);\
    if(fx==fy)return 0;\
    if(sz[fx]>sz[fy])fx^=fy^=fx^=fy;\
    fa[fx]=fy,sz[fy]+=sz[fx];\
    return 1;\
}
inline int read()
{
    int num=0,f=1;char c=getchar();
    while(c<48||c>57){if(c=='-')f=-1;c=getchar();}
    while(c>47&&c<58)num=num*10+(c^48),c=getchar();
    return num*f;
}
inline int re1d()
{
    char c=getchar();
    while(c<48||c>49)c=getchar();
    return c&1;
}
#ifdef cmlBIT
struct BIT{int a[1<<20|1],n;
void add(int x,int p){while(x<=n)a[x]+=p,x+=x&-x;}
int operator[](int x){int res=0;while(x)res+=a[x],x-=x&-x;return res;}
int operator()(int l,int r){return (*this)[r]-(*this)[l-1];}};
#endif
int rnv[1000005];
// #define COMB
#ifdef COMB
#ifndef int
#define int long long
#endif
int fac[1000005],inv[1000005];
#endif
void initprog()
{
#ifdef COMB
	fac[0]=inv[0]=inv[1]=1;
	rg(1000000)fac[i]=fac[i-1]*i%mod;gr
	rg(1000000)if(i>1)inv[i]=inv[mod%i]*(mod-mod/i)%mod;gr
	rg(1000000)rnv[i]=inv[i];gr
	rg(1000000)inv[i]=inv[i]*inv[i-1]%mod;gr
#endif
}
#ifdef COMB
int C(int n,int m)
{
	if(n==m||m==0)return 1;
	if(n<m)return 0;
	return fac[n]*inv[m]%mod*inv[n-m]%mod;
}
#endif
inline int qp(int a,int b){int c=1;while(b){if(b&1)c=c*a%mod;a=a*a%mod;b>>=1;}return c;}
inline int mae(int &a,int b){a+=b;if(a>=mod)a-=mod;return a;}
inline int mde(int &a,int b){a+=mod-b;if(a>=mod)a-=mod;return a;}
inline int mle(int &a,int b){a=a*b%mod;return a;}
inline int mve(int &a,int b){a=a*qp(b,mod-2)%mod;return a;}
inline int mxe(int &a,int b){return a=a>b?a:b;}
inline int mne(int &a,int b){return a=a<b?a:b;}
inline int ae(int a,int b){int c=a+b;return c>=mod?c-mod:c;}
inline int de(int a,int b){return ae(a,mod-b);}
inline int me(int a,int b){return a*b%mod;}
inline int mive(int &a,int b){a=a*rnv[b]%mod;return a;}
inline int ive(int a,int b){return a*rnv[b]%mod;}
inline int ve(int a,int b){return a*qp(b,mod-2)%mod;}
#ifdef cmlST
struct STmin{
	int a[21][1000005],n;
	void init(int N,int *b)
	{
		n=N;
		rg(n)a[0][i]=b[i];gr
		rg(20)rg_(j,n-(1<<i)+1)a[i][j]=min(a[i-1][j],a[i-1][j+(1<<i-1)]);gr gr
	}
	int q(int l,int r)
	{
		int d=std::__lg(r-l+1);
		return min(a[d][l],a[d][r-(1<<d)+1]);
	}
};
struct STmax{
	int a[21][1000005],n;
	void init(int N,int *b)
	{
		n=N;
		rg(n)a[0][i]=b[i];gr
		rg(20)rg_(j,n-(1<<i)+1)a[i][j]=max(a[i-1][j],a[i-1][j+(1<<i-1)]);gr gr
	}
	int q(int l,int r)
	{
		int d=std::__lg(r-l+1);
		return max(a[d][l],a[d][r-(1<<d)+1]);
	}
};
#endif
#ifdef cmlSAM
struct SAM{
	int ch[1000005][26],lnk[1000005],len[1000005],lst=1,cc=1;
	int sz[1000005];
	void insert(int c)
	{
		len[++cc]=len[lst]+1;sz[cc]=1;
		int p=lst;lst=cc;
		while(p&&ch[p][c]==0)ch[p][c]=cc,p=lnk[p];
		if(p==0)lnk[cc]=1;
		else
		{
			int x=ch[p][c];
			if(len[p]+1==len[x])lnk[cc]=x;
			else
			{
				int q=cc;++cc;
				lnk[cc]=lnk[x];
				lnk[x]=lnk[q]=cc;
				len[cc]=len[p]+1;
				memcpy(ch[cc],ch[x],sizeof(ch[cc]));
				while(p&&ch[p][c]==x)ch[p][c]=cc,p=lnk[p];
			}
		}
	}
	newe(1000005);
	long long ans;
	void build()
	{
		rg(cc)addedge(lnk[i],i,0);gr
	}
	void dfs(int u)
	{
		fe(u)dfs(v),sz[u]+=sz[v];gr
		if(sz[u]>1)ans=max(ans,1ll*sz[u]*len[u]);
	}
}t;
#endif
int w[1234567];
newe(1234567);
#define double modint
inline modint qpow(modint x,int y){return x^y;}
using vi=std::vector<double>;
vi operator+(vi a,vi b)
{
	vi c=a;
	for(int i=0;i<b.size();i++)c[i]+=b[i];
	return c;
}
vi operator*(vi a,double b)
{
	vi c=a;
	for(int i=0;i<c.size();i++)c[i]*=b;
	return c;
}
vi operator-(vi a,vi b)
{
	vi c=a;
	for(int i=0;i<b.size();i++)c[i]-=b[i];
	return c;
}
vi operator-(vi a)
{
	vi c=a;
	for(int i=0;i<c.size();i++)c[i]=-c[i];
	return c;
}
mgs
using std::vector;
vector<vi>A;
int cc=0,n,m,k;
std::pair<int,vi> dfs(int u,int fa,int ed)
{
	if(u==ed)return {1,vi(n+3)};
	fe(u)
	if(v==fa)continue;
	auto [AA,B]=dfs(v,u,ed);
	if(AA)return std::pair<int,vi>{1,B+A[i]*(double)e[i].w};
	gr
	
	return {0,vi()};
}
std::vector<std::pair<modint,int> >E[2000];
void add(int u,int v,modint c)
{
	if(uf(u,v))
	{
		++cc;
		A[cnt][cc]=1;E[u].push_back({c,cnt});
		addedge(u,v,c);
		A[cnt][cc]=mod-1;E[v].push_back({c,cnt});
		addedge(v,u,c);
	}
	else
	{
		if(!c.x)return;
		vi t=dfs(u,0,v).second*((mod-1)/c);
		E[u].push_back({c,cnt});A[cnt]=-t;
		++cnt;
		E[v].push_back({c,cnt});A[cnt]=t;
		++cnt;
	}
}
int ff[2000];
namespace GX{
double a[2000][2000];
bool eqaq(double a,double b)
{
	return a.x==b.x;
}
inline void swap(double &a,double &b)
{
	double t=a;a=b,b=t;
}
int main(int n)
{
	//// for(int j=0;j<=n;j++)printf("%.3lf ",a[i][j]);
		// for(int i=0;i<n;i++,puts(""))
			// for(int j=0;j<=n;j++)printf("%.2lf ",a[i][j]);puts("");
	for(int i=0;i<n;i++)
	{
		int amxn=i;
		for(int j=i+1;j<n;j++)if((a[j][i].x)>(a[amxn][i].x))amxn=j;
		for(int j=0;j<=n;j++)swap(a[i][j],a[amxn][j]);
		if(eqaq(a[i][i],0))return puts("-1"),exit(0),0;
	
		for(int j=i+1;j<=n;j++)a[i][j]/=a[i][i];
		a[i][i]=1.0;
		for(int j=0;j<n;j++)
		{
			if(i^j)
			{
				for(int k=i+1;k<=n;k++)a[j][k]-=a[j][i]*a[i][k];
				a[j][i]=0;
			}
		}
			
		
	//	for(int i=0;i<n;i++,puts(""))
	//		for(int j=0;j<=n;j++)printf("%.2lf ",a[i][j]);puts("");
	}
	// for(int i=0;i<n;i++)printf("%.2lf\n",a[i][n]);
	return 0;
}
}
namespace awa{
	mgs
};
signed main()
{
	initprog();
	int T=read();while(T--)
	{
	cnt=2;
	// freopen("pipe.in","r",stdin);
	// freopen("pipe.out","w",stdout);
	n=read(),m=read(),k=1;
	
	rg(n+m+m+n+3)h[i]=0,ff[i]=0,E[i].clear();gr
	rg(n+m+m+n+3)rg_(j,max(n,m)+3)GX::a[i][j]=0;gr gr A.clear();
	cc=0;
	
	
	A=vector<vi>(66666,vi(n+3));
	rg(n+1)fa[i]=i,sz[i]=1;gr
	rg(n+1)awa::fa[i]=i,awa::sz[i]=1;gr
	int s=0;
	rg(n)s+=w[i]=(i==n);gr
	rg(k)
	int x=1;
	add(n+1,x,0);
	awa::uf(n+1,x);
	gr
	n++;
	
std::map<int,vector<std::pair<int,int>> >ww;
	rg(m)
	int u=read(),v=read(),c=read();
	// add(u,v,c);
	ww[c].push_back({u,v});
	awa::uf(u,v);
	gr
	rg(n)ff[awa::f(i)]+=w[i];gr
	rg(n)if(awa::f(i)!=awa::f(n)&&awa::f(i)==i&&ff[i]==0)add(n+1,i,0);gr
	
	for(auto[i,W]:ww)for(auto[u,v]:W)add(u,v,i);
	
	for(int u=1;u<=n;u++)
	{
		vi S(n+3);
		for(auto [v,id]:E[u])
			S=S+A[id];
		for(int j=1;j<=n;j++)
			GX::a[u-1][j-1]=S[j];
		GX::a[u-1][n-1]=w[u]-(u==n?s:0);
	}
	GX::main(n-1);
	double R=0;
	for(int i=1;i<=n;i++)
		for(auto[c,id]:E[i])
		{
			double s=0;
			for(int j=1;j<=cc;j++)
				s+=GX::a[j-1][n-1]*A[id][j];
			R+=s*s*c;
			// printf("%.2lf %d\n",s,c);
		}
	printf("%d\n",(R/2).x);fflush(stdout);
	}
	return 0;
}