#include<fstream>
#include<vector>
#include<algorithm>
using namespace std;

ifstream cin("pscnv.in");
ofstream cout("pscnv.out");

const int NMAX = 25e4 + 1;

int t[NMAX];

int root(int n)
{
    return t[n] ? t[n] = root(t[n]) : n;
}

struct muchie
{
    int a,b,c;
};

bool cmp(const muchie &a,const muchie &b)
{
    return a.c < b.c;
}

int main()
{
    int n,m,a,b,c,x,y;
    cin >> n >> m >> x >> y; vector<muchie> muchii(m);
    for(int i = 0; i < m ; i++)
        {
            cin >> muchii[i].a >> muchii[i].b >> muchii[i].c;
        }

    sort(muchii.begin(),muchii.end(),cmp);
    for(auto it : muchii)
        {
            int ca = root(it.a),cb = root(it.b);
            if(ca == cb) continue;
            t[ca] = cb;

            int rx = root(x),ry = root(y);
            if(rx == ry)
                {
                    cout << it.c;
                    return 0;
                }

        }

}