#include<bits/stdc++.h>
using namespace std;
int g[305][305];
int n, m, x, y, z, t;
int main() {
	cin >> n >> m >> t;
	memset(g, 0x3f, sizeof(g));
	for (int i = 1; i <= n; i++)
		g[i][i] = -1;
	for (int i = 1; i <= m; i++) {
		cin >> x >> y >> z;
		g[x][y] = z;
	}
	for (int k = 1; k <= n; k++)
		for (int i = 1; i <= n; i++)
			for (int j = 1; j <= n; j++)
				g[i][j] = min(g[i][j], max(g[i][k], g[k][j]));
	for (int i = 1; i <= t; i++) {
		cin >> x >> y;
		if (g[x][y] >= 1e9)cout << -1;
		else cout << g[x][y] << "\n";
	}
	return 0;
}