//s
#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& operator >> (long long &n)
    {
        char c;
        n = 0;
        while (!isdigit(c = read_ch()) && c != '-');
        long long 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;
    }
};

const int NMAX = 25e4 + 5;

int n, m;

int p, q;

int x, y, d;

vector <pair<int, int>> v[NMAX];
bitset <NMAX> visited;

void dfs(int nod, int val)
{
    visited[nod] = true;

    for(auto & i : v[nod])
    {
        if(visited[i.first] == false && i.second <= val)
        {
            dfs(i.first, val);
        }
    }
}

inline bool verif(int val)
{
    visited &= 0;
    dfs(p, val);

    return visited[q];
}

int main()
{

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

    f >> n >> m >> p >> q;

    for(int i = 1; i <= m; i ++)
    {
        f >> x >> y >> d;

        v[x].push_back(make_pair(y, d));
        v[y].push_back(make_pair(x, d));
    }

    int st = 1;

    int dr = 1e3;

    int res;

    while(st <= dr)
    {
        int mij = (st + dr) / 2;

        if(verif(mij))
        {
            res = mij;
            dr = mij - 1;
        }
        else
        {
            st = mij + 1;
        }
    }

    g << res;

    return 0;
}