#include <bits/stdc++.h>
using namespace std;


ifstream fin ("pscnv.in");
ofstream fout ("pscnv.out");

const int NMAX = 250005;

const int MMAX = 500005;

int t[NMAX], node1, node2, n, m;

struct T
{
    int x, y, val;
};
T a[MMAX];


inline bool CMP(const T A, const T B)
{
    return A . val < B . val;
}

inline void Union(int x, int y)
{
    t[y] = x;
}

inline int Find(int x)
{
    int rad, y;
    rad = x;
    while(t[rad])
        rad = t[rad];
    while(x != rad)
    {
        y = t[x];
        t[x] = rad;
        x = y;
    }
    return x;
}

int main()
{
    int x, y;
    fin >> n >> m >> node1 >> node2;
    for(int i = 1 ; i <= m ; i++)
        fin >> a[i] . x >> a[i] . y >> a[i] . val;
    sort(a + 1, a + m + 1, CMP);
    for(int i = 1 ; i <= m ; i++)
    {
        x = Find(a[i] . x);
        y = Find(a[i] . y);
        if(x != y)
            Union(x, y);

        x = Find(node1);
        y = Find(node2);
        if(x == y)
        {
            fout << a[i] . val << "\n";
            return 0;
        }
    }
    fin.close();
    fout.close();
    return 0;
}