#include <bits/stdc++.h>
using namespace std;
ifstream f("pscnv.in");
ofstream g("pscnv.out");
struct pt{
    int x,y,c;
}v[1<<19];
int i,n,m,x,y,G[1<<18];
bool cmp(pt a,pt b){
    return a.c<b.c;
}
int gr(int i){
    if(i!=G[i]) G[i]=gr(G[i]);
    return G[i];
}
int main(){
    f>>n>>m>>x>>y;
    for(i=1;i<=m;++i) f>>v[i].x>>v[i].y>>v[i].c;
    sort(v+1,v+m+1,cmp);
    for(i=1;i<=n;++i) G[i]=i;
    for(i=1;i<=m;++i){
        if(gr(v[i].x)!=gr(v[i].y))
            G[v[i].x]=v[i].y;
        if(gr(x)==gr(y)){
            g<<v[i].c;
            return 0;
        }
    }
}