///TEST ESTT STTE TTES TEST
///TEST ESTT STTE TTES TEST
///TEST ESTT STTE TTES TEST
///TEST ESTT STTE TTES TEST
#include<fstream>
#include<algorithm>
using namespace std;


ifstream f("pscnv.in");
ofstream g("pscnv.out");
int X,Y,T[250000],n,m,a,b,k,i;
struct muchii{
    int x,y,c;
};
muchii v[500007];


struct  cmp{
    bool operator ()(const muchii a,const muchii b)const{
        return a.c<b.c;
    }

};
int tata(int x)
{
    if(x!=T[x])
        T[x]=tata(T[x]);
    return T[x];
}
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+1+m,cmp());


    for(i=1;i<=n;i++)
        T[i]=i;

    i=1;
    while(i<=m) {

        a=tata(v[i].x);
        b=tata(v[i].y);

        if(a!=b){
            if(v[i].c>k)
                k=v[i].c;
            T[b]=a;
        }
        if(T[X]==T[Y])
            break;
        i++;
    }
    g<<k<<"\n";
    return 0;
}