#include <bits/stdc++.h>
#define ll long long int
#define ep1 1000000ll
#define ep2 1000000000000ll
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];
ll v[500001];

int fi(const int &a)
{
    if (a==p[a])
        return a;
    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;
        ll e=ep2*c + ep1*a + b;
        v[i]=e;
    }
    sort(v+1,v+m+1);

    for (i=1;i<=m;++i)
    {
        c=v[i]/ep2;v[i]%=ep2;
        a=v[i]/ep1;v[i]%=ep1;
        b=v[i];
        if(p[a] == 0) p[a] = a;
        if(p[b] == 0) p[b] = b;

        if (fi(a)!=fi(b))
            p[a]=p[b];
        if (fi(x)==fi(y))
        {
            g<<c;
            return 0;
        }
    }
}