#include <bits/stdc++.h>
using namespace std;
string z = "pscnv.";

ifstream f(z+"in");
ofstream g(z+"out");

int i,n,k,a,r,b,c,x,y,m,fv[500001],p[250001];
tuple<int,int,int> v[500001];

int fi(const int &a)
{
    if (a!=p[a])
        return p[a]=fi(p[a]);
    return p[a];
}

int main()
{

    f>>n>>m>>x>>y;
    for (i=1;i<=m;++i)
    {
        f>>a>>b>>c;
        tuple<int,int,int> e(c,a,b);
        v[i]=e;
    }
    sort(v+1,v+m+1);
    for(i=1;i<=n;++i)
        p[i]=i;
    for (i=1;i<=m;++i)
    {
        c=get<0>(v[i]);
        a=get<1>(v[i]);
        b=get<2>(v[i]);;
        if (fi(a)!=fi(b))
            p[a]=p[b];
        if (fi(x)==fi(y))
        {
            g<<c;
            return 0;
        }
    }
}