//solutia cu dijkstra
#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>

using namespace std;

const char iname[] = "pscnv.in";
const char oname[] = "pscnv.out";
const int  nmax    = 100005;
const int  infinite= 2188989;

vector<pair <int, int > > Gr[nmax];
int n, m, i, x, y, c, a1, a2;
int Cost[nmax];
bool viz[nmax];
int extracted;

struct cmp
{
	bool operator()(const int &a, const int &b)const
	{
		return (Cost[a] > Cost[b]);
	}
};


priority_queue<int, vector<int>, cmp> Q;

void dijkstra()
{
	Q.push(1);
	viz[a1] = 1;
	Cost[a1] = 299999;
	while(!Q.empty())
	{
		extracted = Q.top();
		Q.pop();
		viz[extracted] = 0;
		for(vector<pair <int, int> >::iterator it = Gr[extracted].begin(); it != Gr[extracted].end(); ++it)
		{	
			
				if(Cost[(*it).first] > max(Cost[extracted], (*it).second))
				{
					Cost[(*it).first] = max(Cost[(*it).first],min(Cost[extracted], (*it).second));
					Q.push((*it).first);
				}
		}
	}
}
	

int main()
{	
	
	freopen(iname, "r", stdin);
	freopen(oname, "w", stdout);
	scanf("%d %d %d %d", &n, &m, &a1, &a2);
	for(i = 1; i <= m; i ++)
	{
		scanf("%d %d %d", &x, &y, &c);
		Gr[x].push_back(make_pair(y, c));
		Gr[y].push_back(make_pair(x, c));
	}
	
	dijkstra();
	printf("%d\n", Cost[a2]);
	return 0;
}