#include <cstdio>
#include <iostream>
#include <algorithm>
#include <ctype.h>
#include <vector>
#define MMAX 500000
#define NMAX 250000

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;
	}
};

int n, m, x, y, ans, tata[NMAX+10], rang[NMAX+10], i, val1, val2, v1, v2;
struct date
{   int nod1, nod2, cost;
}K[MMAX+10];
vector <pair <int, int> > nod[NMAX+10];

bool mycmp(date a, date b)
{   if(a.cost < b.cost) return 1;
    return 0;
}

int findDaddy(int x)
{   v1 = x;
    v2 = x;
    while(tata[v2] != v2) v2 = tata[v2];
    while(tata[x] != x)
        {   v1 = tata[x];
            tata[x] = v2;
            x = v1;
        }
    return v2;
}

void unite(int x, int y)
{   if(rang[x] < rang[y]) tata[x] = y;
    else tata[y] = x;

    if(rang[x] == rang[y]) rang[x]++;
}

void dfs(int x, int p, int c)
{   if(x == y)
        {   ans = c;
            return;
        }
    for(int i=0; i<nod[x].size(); i++)
        if(nod[x][i].first != p) dfs(nod[x][i].first, x, max(c, nod[x][i].second));
}

int main()
{
    InParser f("pscnv.in");
    freopen("pscnv.out", "w", stdout);
    f >> n >> m >> x >> y;
    for(i=1; i<=n; i++) tata[i] = i, rang[i] = 1;
    for(i=1; i<=m; i++)
        {   int nod1, nod2, cost;
            f >> K[i].nod1 >> K[i].nod2 >> K[i].cost;
        }
    sort(K+1, K+m+1, mycmp);
    for(i=1; i<=m; i++)
        {   val1 = findDaddy(K[i].nod1);
            val2 = findDaddy(K[i].nod2);
            if(val1 == val2) continue;
            nod[K[i].nod1].push_back({K[i].nod2, K[i].cost});
            nod[K[i].nod2].push_back({K[i].nod1, K[i].cost});
            unite(val1, val2);
        }
    dfs(x, 0, 0);
    printf("%d\n", ans);
    return 0;
}