#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
typedef long long ll;
priority_queue<pair<pair<ll,ll>,pair<vector<bool>,int>>,vector<pair<pair<ll,ll>,pair<vector<bool>,int>>>,greater<pair<pair<ll,ll>,pair<vector<bool>,int>>>> pq;
ll dp[71][71];
ll path[71][71];
int n,m,k,q;
int a,b,t;
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m;
for(int i = 0; i < m; i++) {
cin >> a >> b >> t;
if(path[a][b] == 0 || path[a][b] > t) path[a][b] = t;
}
cin >> k >> q;
for(int i = 1; i <= n; i++) {
vector<bool> temp(71,false);
for(int j = 1; j <= 70; j++) {
dp[i][j] = -1;
}
dp[i][i] = 0;
pq.push({{0,i},{temp,0}});
while(!pq.empty()) {
ll a = pq.top().first.first;
ll b = pq.top().first.second;
vector<bool> checked = pq.top().second.first;
int cnt = pq.top().second.second;
pq.pop();
if(cnt >= k) continue;
if(checked[b]) continue;
checked[b] = true;
for(int j = 1; j <= n; j++) {
if(path[b][j] != 0 && !checked[j]) {
pq.push({{a + path[b][j],j},{checked,cnt+1}});
if(dp[i][j] == -1 || dp[i][j] > a + path[b][j]) {
dp[i][j] = a + path[b][j];
}
}
}
}
}
for(int i = 0; i < q; i++) {
cin >> a >> b;
cout << dp[a][b] << endl;
}
return 0;
}
