#include <iostream>
#include <cstring>
#include <vector>
#include <queue>
using namespace std;
#define ll long long
int n, m, k, q;
vector<pair<int, int> > adjl[75];
bool check(ll time, int c, int d){
queue<pair<int, pair<int, ll> > > q;
q.push(make_pair(c, make_pair(0, 0)));
while(!q.empty()){
pair<int, pair<int, int> > iii = q.front(); q.pop();
if(iii.second.first > k) continue;
if(iii.second.second > time) continue;
if(iii.first == d) return true;
for(int i = 0; i < (int)adjl[iii.first].size(); i++){
q.push(make_pair(adjl[iii.first][i].first, make_pair(iii.second.first + 1, iii.second.second + adjl[iii.first][i].second)));
}
}
return false;
}
int main(){
cin >> n >> m;
for(int i = 0; i < m; i++){
int a, b, t; cin >> a >> b >> t;
adjl[a].push_back(make_pair(b, t));
}
cin >> k >> q;
for(int i = 0; i < q; i++){
int c, d; cin >> c >> d;
ll lower = 0;
ll upper = 1000000000000;
while(lower < upper){
ll mid = (ll)(lower + upper) / 2;
if(check(mid, c, d))upper = mid;
else lower = mid + 1;
}
if(upper == 1000000000000 && !check(upper, c, d)) cout << -1;
else cout << lower;
cout << "\n";
}
}
