/*
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,fma,bmi,bmi2,sse4.2,popcnt,lzcnt")
*/
#include <bits/stdc++.h>
#define taskname ""
#define all(x) x.begin(), x.end()
#define ll long long
#define ld long double
#define pb push_back
#define ff first
#define ss second
#define pii pair<int, int>
#define vi vector<int>
using namespace std;
const int mxN = 3e6 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n, m, k, q;
int dp[75][75][75];
int single_path[75][75];
pii res[75][75];
void solve() {
cin >> n >> m;
memset(dp, 0x3f, sizeof dp);
memset(single_path, 0x3f, sizeof single_path);
for(int i = 1; i <= m; ++i) {
int u, v, w;
cin >> u >> v >> w;
dp[1][u][v] = min(dp[1][u][v], w);
single_path[u][v] = min(single_path[u][v], w);
}
cin >> k >> q;
for(int turn = 2; turn <= min(n, k); ++turn)
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
for(int k = 1; k <= n; ++k)
dp[turn][i][k] = min({dp[turn][i][k], mod, dp[turn - 1][i][j] + single_path[j][k]});
while(q--) {
int u, v; cin >> u >> v;
if(u == v) {
cout << "0\n";
continue;
}
int ans = mod;
for(int i = 1; i <= min(n, k); ++i)
ans = min(ans, dp[i][u][v]);
if(ans >= mod) cout << "-1\n";
else cout << ans << "\n";
}
}
signed main() {
#ifndef CDuongg
if(fopen(taskname".inp", "r"))
assert(freopen(taskname".inp", "r", stdin)), assert(freopen(taskname".out", "w", stdout));
#else
freopen("bai3.inp", "r", stdin);
freopen("bai3.out", "w", stdout);
auto start = chrono::high_resolution_clock::now();
#endif
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1; //cin >> t;
while(t--) solve();
#ifdef CDuongg
auto end = chrono::high_resolution_clock::now();
cout << "\n"; for(int i = 1; i <= 100; ++i) cout << '=';
cout << "\nExecution time: " << chrono::duration_cast<chrono::milliseconds> (end - start).count() << "[ms]" << endl;
#endif
}
