#include <bits/stdc++.h>
using namespace std;
long long dist[75][75];
long long f[75][75][75];
int n, m;
int lim, q;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> m;
memset(dist, 0x3f, sizeof(dist));
memset(f, 0x3f, sizeof(f));
const long long INF = dist[0][0];
for (int i = 0; i <= n; i++)
dist[i][i] = 0,
f[1][i][i] = 0;
while (m--) {
int u, v, w;
cin >> u >> v >> w;
dist[u][v] = min(dist[u][v], 1ll * w);
f[1][u][v] = dist[u][v];
}
cin >> lim >> q;
lim = min(lim, n-1);
for (int t = 2; t <= lim; t++) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
for (int k = 1; k <= n; k++)
f[t][i][j] = min(f[t][i][j], f[t - 1][i][k] + dist[k][j]);
}
}
}
while (q--) {
int u, v;
cin >> u >> v;
long long ans = INF;
for (int t = 0; t <= lim; t++)
ans = min(ans, f[t][u][v]);
if (ans == INF)
cout << -1 << "\n";
else cout << ans << "\n";
}
return 0;
}
