#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;
    }
};

class OutParser {
private:
    FILE *fout;
    char *buff;
    int sp;

    void write_ch(char ch) {
        if (sp == 50000) {
            fwrite(buff, 1, 50000, fout);
            sp = 0;
            buff[sp++] = ch;
        } else {
            buff[sp++] = ch;
        }
    }

public:
    OutParser(const char* name) {
        fout = fopen(name, "w");
        buff = new char[50000]();
        sp = 0;
    }

    ~OutParser() {
        fwrite(buff, 1, sp, fout);
        fclose(fout);
    }

    OutParser& operator << (int vu32) {
        if (vu32 <= 9) {
            write_ch(vu32 + '0');
        } else {
            (*this) << (vu32 / 10);
            write_ch(vu32 % 10 + '0');
        }
        return *this;
    }

    OutParser& operator << (char ch) {
        write_ch(ch);
        return *this;
    }

    OutParser& operator << (const char *ch) {
        while (*ch) {
            write_ch(*ch);
            ++ch;
        }
        return *this;
    }
};

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

int N, M, x, y, wt;
vector<vector<pair<int,int>>> G;
vector<bool> vis;

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

bool check(int w) {
    wt = w;
    vis = vector<bool>(N + 1);
    dfs(x);
    return vis[y];
}

int main() {
    fin >> N >> M >> x >> y;
    G.resize(N + 1);
    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;
}