卒

#include <bits/stdc++.h>
#define int long long
using namespace std;
int n, m, s, t, h[20001], c, ans = 1e9;
struct Egde{int nxt, dis, to;}e[10001];
bool vis[20001];
void dfs (int d, int mx)
{
	if (mx >= ans)return;
	if (d == t)
	{
		ans = mx;
		return;
	}
	for (int i = h[d]; i != 0; i = e[i].nxt)if (! vis[e[i].to])dfs (e[i].to, max (mx, e[i].dis));
}
void add (int from, int to, int dis)
{
	e[++ c].nxt = h[from];
	e[c].dis = dis;
	e[c].to = to;
	h[from] = c;
}
signed main()
{
	scanf ("%d %d %d %d", &n, &m, &s, &t);
	for (int i = 0; i < m; ++ i)
	{
		int u, v, d;
		scanf ("%d %d %d", &u, &v, &d);
		add (u, v, d);
		add (v, u, d); 
	}
	dfs (s, 0);
	printf ("%d", ans);
	return 0;
}