#include <bits/stdc++.h>
using namespace std;
#define TRACE(x) cerr << __LINE__ << ": " << #x << " = " << x << endl
#define _ << " _ " <<
template<class> struct is_container : false_type {};
template<class... Ts> struct is_container<vector<Ts...>> : true_type {};
template<class... Ts> struct is_container<map<Ts...>> : true_type {};
template<class... Ts> struct is_container<unordered_map<Ts...>> : true_type {};
template<class... Ts> struct is_container<set<Ts...>> : true_type {};
template<class... Ts> struct is_container<unordered_set<Ts...>> : true_type {};
template<class... Ts> struct is_container<multiset<Ts...>> : true_type {};
template<class... Ts> struct is_container<unordered_multiset<Ts...>> : true_type {};
template<class T, class = typename enable_if<is_container<T>::value>::type>
ostream& operator<<(ostream &o, T x) {
int f = 1;
o << "{";
for (auto y : x) {
o << (f ? "" : ", ") << y;
f = 0;
}
return o << "}";
}
template<class T, class U>
ostream& operator<<(ostream &o, pair<T, U> x) {
return o << "(" << x.first << ", " << x.second << ")";
}
#define fi first
#define se second
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
const int INF = 1e9;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n >> m;
vector<vi> e(n, vi(n, INF));
for (int i = 0; i < n; i++) e[i][i] = 0;
while (m--) {
int x, y, w;
cin >> x >> y >> w;
x--; y--;
e[x][y] = min(e[x][y], w);
}
int k;
cin >> k;
k = min(k, n);
auto sol = e;
while (--k) {
auto new_sol = sol;
for (int x = 0; x < n; x++)
for (int y = 0; y < n; y++)
for (int z = 0; z < n; z++)
new_sol[x][y] = min(new_sol[x][y], sol[x][z] + e[z][y]);
sol = new_sol;
}
int q;
cin >> q;
while (q--) {
int x, y;
cin >> x >> y;
x--; y--;
if (sol[x][y] == INF) sol[x][y] = -1;
cout << sol[x][y] << '\n';
}
return 0;
}
