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

ifstream f("pscnv.in");
ofstream g("pscnv.out");

int n, m, x, y, v[250005];

struct edge
{
    int src, des, cost;
}edges[500005];

bool cmp(edge x, edge y)
{
    return x.cost < y.cost;
}

int father(int node)
{
    while(v[node] != node)
        node = v[node];
    return node;
}

int main()
{
    f >> n >> m >> x >> y;

    for(int i = 0; i < m; i++)
    {
        f >> edges[i].src >> edges[i].des >> edges[i].cost;
    }

    for(int i = 1; i <= n; i++)
    {
        v[i] = i;
    }

    sort(edges, edges + m, cmp);

    for(int i = 0; i < m; i++)
    {
        if(father(edges[i].src) != father(edges[i].des))
            v[edges[i].des] = edges[i].src;

        if(father(x) == father(y))
        {
            g << edges[i].cost;
            break;
        }

    }

    f.close();
    g.close();
    return 0;
}