#include <fstream>
#include <vector>
#include <iostream>
#include <bitset>
#include <stack>
#define pii pair <int, int>
#include <stdlib.h>
#include <set>

using namespace std;

const int N = 250005, oo = 2e9;
int n, startnode, endnode, maxcost;
set <pii> L[N];
set <pii> :: iterator it;
bitset <N> seen;
stack <int> st;

void Read ()
{
    ifstream fin ("pscnv.in");
    int m, x, y, cost;
    fin >> n >> m >> startnode >> endnode;
    for (int i = 1; i <= m; i++)
    {
        fin >> x >> y >> cost;
        L[x].insert({cost, y});
        L[y].insert({cost, x});
        maxcost = max(maxcost, cost);
    }
}

bool DFS (int node, int cost)
{
    st.push(node);
    while (!st.empty())
    {
        int k = st.top();
        seen[k] = 1;
        if (L[k].size())
        {
            bool valid = false;
            for (it = L[k].begin(); it != L[k].end(); it++)
                if (!seen[it -> second] && it -> first <= cost)
                {
                    valid = true;
                    if (it -> second == endnode)
                        return true;
                    else st.push(it -> second);
                }
            if (!valid) st.pop();
        }
        else
            st.pop();
    }
    return false;
}

bool IsValidPath (int k)
{
    seen.reset();
    return (DFS(startnode, k));
}

int BinSearch ()
{
    int left, right, mid, ans;
    left = 1;
    right = maxcost;
    while (left <= right)
    {
        mid = (left + right) / 2;
        if (IsValidPath(mid))
        {
            ans = mid;
            right = mid - 1;
        }
        else left = mid + 1;
    }
    return ans;
}

void Solve ()
{

    ofstream fout ("pscnv.out");
    fout << BinSearch() << "\n";
    fout.close();
}

int main()
{
    Read();
    Solve();
    return 0;
}