#include <bits/stdc++.h>
using namespace std;
#define union Union
int n, m, father[1005], ans;
struct node {
	int x, y, z;
}a[100005];
int find(int x)
{
	if (father[x] == x)
	{
		return x;
	}
	return father[x] = find(father[x]);
}
void union(int x, int y)
{
	x = find(x);
	y = find(y);
	if (x != y)
	{
		father[x] = y;
	}
	return ;
}
bool cmp(node x, node y)
{
	return x.z < y.z;
}
void kruskal()
{
	int cnt = 0;
	sort(a + 1, a + 1 + m, cmp);
	for (int i = 1 ; i <= m ; i++)
	{
		if (find(a[i].x) != find(a[i].y))
		{
//			union(a[i].x, a[i].y);
			ans = a[i].z;
			cnt ++;
			if (cnt == n - 1)
			{
				cout << ans;
				exit(0);
			}
		}
	}
	cout << -1;
	return;
}
int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n >> m;
	for (int i = 1 ; i <= n ; i++)
	{
		father[i] = i;
	}
	for (int i = 1 ; i <= m ; i++)
	{
		cin >> a[i].x >> a[i].y >> a[i].z;
	}
	kruskal();
	return 0;
 }