#include <bits/stdc++.h>
#define int long long
using namespace std;
const long long N = 76;
int dp[N][N][N];
void solve()
{
int n, m;
cin >> n >> m;
for (int i = 0; i < N; i++)
for (int j = 0; j < N; j++)
for (int k = 0; k < N; k++)
dp[i][j][k] = 1e18;
for (int i = 0; i < N; i++)
{
for (int k = 0; k < N; k++)
{
dp[i][i][k] = 0;
}
}
int u, v, d;
for (int i = 0; i < m; i++)
{
cin >> u >> v >> d;
dp[u][v][1] = min(d, dp[u][v][1]);
}
int k, q;
cin >> k >> q;
k = min(k, 73LL);
for (int i = 2; i <= k; i++)
{
for (int mid = 1; mid <= n; mid++)
{
for (int u = 1; u <= n; u++)
{
for (int v = 1; v <= n; v++)
{
dp[u][v][i] = min(dp[u][v][i], dp[u][v][i - 1]);
dp[u][v][i] = min(dp[u][v][i], dp[u][mid][i - 1] + dp[mid][v][1]);
}
}
}
}
// cout << dp[1][4][2] << endl;
for (int i = 0; i < q; i++)
{
cin >> u >> v;
if (dp[u][v][k] == 1e18)
{
cout << -1 << endl;
}
else
cout << dp[u][v][k] << endl;
}
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
int t = 1;
// cin >> t;
for (int i = 1; i <= t; i++)
{
// cout << "Case #" << i << ':' << ' ';
solve();
cout << endl;
}
return 0;
}
