#include<bits/stdc++.h>
using namespace std;
const int maxn=2500;
int n,m,mod;
int tot=1,pre[maxn],son[maxn],now[maxn],id[maxn],w[maxn];
int dep[maxn],fa[maxn],upv[maxn],vis[maxn],ok[maxn];
int bs=-1,sum=0;
vector<int> S,T;
vector<pair<int,vector<int> > > ans;
void put(int x,int y,int z)
{
	pre[++tot]=now[x];
	now[x]=tot;
	son[tot]=y;
	id[tot]=z;
}
void add(int p,int q,int v)
{
	sum=(sum+v)%mod;
	T.clear();T.push_back(q);
	for(auto t:S)
		if(t!=p)
			T.push_back(t);
	sort(T.begin(),T.end());
	ans.emplace_back(v,T);
}
int power(int x,int y)
{
	int ans=1;
	while(y)
	{
		if(y&1)
			ans=1ll*ans*x%mod;
		y>>=1;
		x=1ll*x*x%mod;
	}
	return ans;
}
void dfs1(int x,int ff,int pp)
{
	fa[x]=ff;dep[x]=dep[ff]+1;
	for(int p=now[x];p;p=pre[p])
	{
		if(p==(pp^1))
			continue;
		int t=son[p];
		if(dep[t])
		{
			if(dep[t]<dep[x])
			{
				int l=x;
				while(l!=t)
					vis[l]++,l=fa[l];
			}
			continue;
		}
		upv[t]=id[p];
		S.push_back(id[p]);
		dfs1(t,x,p);
		if(!vis[t])
		{
			if(bs==-1)
				bs=w[id[p]];
			else if(bs!=w[id[p]])
			{
				puts("-1");
				exit(0);
			}
		}
	}
}
void dfs2(int x,int pp)
{
	ok[x]=1;
	for(int p=now[x];p;p=pre[p])
		if(p!=(pp^1))
		{
			int t=son[p];
			if(dep[t]>dep[x])
				continue;
			vector<int> ed;
			int l=x;
			while(l!=t)
			{
				vis[l]--;
				if(!vis[l])
					ed.push_back(upv[l]);
				l=fa[l];
			}
			for(auto tt:ed)
				add(tt,id[p],(bs-w[tt]+mod)%mod),w[id[p]]=(0ll+w[id[p]]-bs+w[tt]+mod)%mod,w[tt]=bs;
			l=x;
			while(l!=t)
			{
				if(vis[l]&&w[id[p]])
					add(upv[l],id[p],w[id[p]]),(w[upv[l]]+=w[id[p]])%=mod,w[id[p]]=0;
				l=fa[l];
			}
			if(w[id[p]])
			{
				puts("-1");
				exit(0);
			}
		}
	for(int p=now[x];p;p=pre[p])
	{
		int t=son[p];
		if(ok[t]||p==(pp^1))
			continue;
		dfs2(t,p);
	}
}
int main()
{
	scanf("%d%d%d",&n,&m,&mod);
	int s=0;
	for(int i=1,u,v;i<=m;i++)
		scanf("%d%d%d",&u,&v,&w[i]),put(u,v,i),put(v,u,i),s=(s+w[i])%mod;
	dfs1(1,0,0);
	if(bs==-1)
		bs=1ll*s*power(n-1,mod-2)%mod;
	dfs2(1,0);
	add(*S.begin(),*S.begin(),(bs-sum+mod)%mod);
	printf("%d\n",(int)ans.size());
	for(auto [x,y]:ans)
	{
		printf("%d ",x);
		for(auto t:y)
			printf("%d ",t);
		puts("");
	}
	
	return 0; 
}