#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define fi first
#define se second
#define For(i, l, r) for (auto i = (l); i < (r); i++)
#define ForE(i, l, r) for (auto i = (l); i <= (r); i++)
#define FordE(i, l, r) for (auto i = (l); i >= (r); i--)
#define Fora(v, a) for (auto v: (a))
#define bend(a) (a).begin(), (a).end()
#define isz(a) ((signed)(a).size())
using ll = long long;
using ld = long double;
using pii = pair <int, int>;
using vi = vector <int>;
using vpii = vector <pii>;
using vvi = vector <vi>;
const int N = 70 + 5, inf = 1e9 + 7;
int n, m;
int adj[N][N];
int dp[N][N][N];
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
// freopen("KEK.inp", "r", stdin);
// freopen("KEK.out", "w", stdout);
cin >> n >> m;
ForE(u, 1, n){
ForE(v, 1, n){
adj[u][v] = inf;
}
}
while (m--){
int u, v, w; cin >> u >> v >> w;
adj[u][v] = min(adj[u][v], w);
}
int k, q; cin >> k >> q; k = min(k, n);
ForE(u, 1, n){
ForE(v, 1, n){
dp[0][u][v] = (u == v ? 0 : inf);
}
}
ForE(i, 1, k){
ForE(u, 1, n){
ForE(v, 1, n){
dp[i][u][v] = (u == v ? 0 : inf);
}
}
ForE(w, 1, n){
ForE(u, 1, n){
ForE(v, 1, n){
dp[i][u][v] = min(dp[i][u][v], dp[i - 1][u][w] + adj[w][v]);
}
}
}
}
while (q--){
int u, v; cin >> u >> v;
cout << (dp[k][u][v] == inf ? -1 : dp[k][u][v]) << endl;
}
}
/*
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INPUT |
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OUTPUT |
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*/
