#include <bits/stdc++.h>

using namespace std;

class InParser {
private:
    FILE *fin;
    char *buff;
    int sp;

    char read_ch() {
        ++sp;
        if (sp == 4096) {
            sp = 0;
            fread(buff, 1, 4096, fin);
        }
        return buff[sp];
    }

public:
    InParser(const char* nume) {
        fin = fopen(nume, "r");
        buff = new char[4096]();
        sp = 4095;
    }

    InParser& operator >> (int &n) {
        char c;
        while (!isdigit(c = read_ch()) && c != '-');
        int sgn = 1;
        if (c == '-') {
            n = 0;
            sgn = -1;
        } else {
            n = c - '0';
        }
        while (isdigit(c = read_ch())) {
            n = 10 * n + c - '0';
        }
        n *= sgn;
        return *this;
    }
};

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

const int NMAX = 2e5 + 5e4 + 1;
int N, M, x, y, wt, vis[NMAX], cnt;
vector<pair<int,int>> G[NMAX];

void dfs(int u) {
    vis[u] = cnt;
    for(const auto &v : G[u])
        if(vis[v.first] != cnt && v.second <= wt)
            dfs(v.first);
}

bool check(int w) {
    wt = w;
    ++cnt;
    dfs(x);
    return (vis[y] == cnt);
}

int main() {
    fin >> N >> M >> x >> y;
    int mx = 0;
    while(M--) {
        int u, v, w;
        fin >> u >> v >> w;
        G[u].emplace_back(v, w);
        G[v].emplace_back(u, w);
        mx = max(mx, w);
    }
    int st = 1, dr = mx - 1, ans = mx;
    while(st <= dr) {
        int mid = (st + dr) >> 1;
        if(check(mid)) {
            ans = mid;
            dr = mid - 1;
        }
        else
            st = mid + 1;
    }
    fout << ans;
}