#include<cstdio>
#include<vector>
#include<queue>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<ctime>
#include<random>
#include<assert.h>
#define pb emplace_back
#define mp make_pair
#define fi first
#define se second
#define dbg(x) cerr<<"In Line "<< __LINE__<<" the "<<#x<<" = "<<x<<'\n';
#define dpi(x,y) cerr<<"In Line "<<__LINE__<<" the "<<#x<<" = "<<x<<" ; "<<"the "<<#y<<" = "<<y<<'\n';
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double ld;
typedef pair<int,int>pii;
typedef pair<ll,int>pli;
typedef pair<ll,ll>pll;
typedef pair<int,ll>pil;
typedef vector<int>vi;
typedef vector<ll>vll;
typedef vector<pii>vpii;
typedef vector<pll>vpll;
template<typename T>T cmax(T &x, T y){return x=x>y?x:y;}
template<typename T>T cmin(T &x, T y){return x=x<y?x:y;}
template<typename T>
T &read(T &r){
	r=0;bool w=0;char ch=getchar();
	while(ch<'0'||ch>'9')w=ch=='-'?1:0,ch=getchar();
	while(ch>='0'&&ch<='9')r=r*10+(ch^48),ch=getchar();
	return r=w?-r:r;
}
template<typename T1,typename... T2>
void read(T1 &x,T2& ...y){read(x);read(y...);}
const int N=1010;
int n,m;
vpii eg[N];
struct DSU{
	int fa[N];
	void clear(){for(int i=1;i<=n;i++)fa[i]=i;}
	int getfa(int x){return fa[x]==x?x:fa[x]=getfa(fa[x]);}
	void merge(int x,int y){fa[getfa(x)]=getfa(y);}
}dsu,chk;
int ct=0;
pii e[N];
int vis[N],col[N];
int coe[N];
int dis[N],pre[N];
bool check(int w){
	dsu.clear();
	for(int i=1;i<=ct;i++)if(vis[i])dsu.merge(e[i].fi,e[i].se);
	int fl=0;
	for(auto i:eg[w]){
		e[++ct]=i;col[ct]=w;
		if(!fl && dsu.getfa(i.fi)!=dsu.getfa(i.se)){
			vis[ct]=1;
			coe[w]=ct;
			fl=1;
		}
	}
	if(fl)return 1;
	for(int i=1;i<=ct;i++)dis[i]=N,pre[i]=0;
	queue<int>q;
	for(int i=1;i<=ct;i++)
		if(!vis[i] && dsu.getfa(e[i].fi)!=dsu.getfa(e[i].se)){
			q.push(i);
			dis[i]=0;
		}
	int T=0;
	while(!q.empty()){
		int x=q.front();q.pop();
		if(col[x]==w){
			T=x;
			break;
		}
		if(!vis[x]){
			int v=coe[col[x]];
			if(dis[v]==N){
				dis[v]=dis[x]+1;
				pre[v]=x;
				q.push(v);
			}
		}
		else{
			chk.clear();
			for(int i=0;i<w;i++)if(i!=col[x])chk.merge(e[coe[i]].fi,e[coe[i]].se);
			for(int i=1;i<=ct;i++)
				if(!vis[i] && dis[i]==N && chk.getfa(e[i].fi)!=chk.getfa(e[i].se)){
					dis[i]=dis[x]+1;
					pre[i]=x;
					q.push(i);
				}
		}
	}
	if(!T)return 0;
	while(T){
		vis[T]^=1;
		T=pre[T];
	}
	for(int i=1;i<=ct;i++)if(vis[i])coe[col[i]]=i;
	return 1;
}
signed main(){
	#ifdef do_while_true
//		assert(freopen("data.in","r",stdin));
//		assert(freopen("data.out","w",stdout));
	#endif
	read(n);read(m);
	for(int i=1;i<=m;i++){
		int u,v,w;read(u,v,w);
		eg[w].pb(mp(u,v));
	}
	for(int i=0;i<=n;i++)
		if(eg[i].empty() || !check(i)){
			cout << i << '\n';
			return 0;
		}
    #ifdef do_while_true
//		cerr<<'\n'<<"Time:"<<1.0*clock()/CLOCKS_PER_SEC*1000<<" ms"<<'\n';
	#endif
	return 0;
}