//雪花飄飄北風嘯嘯
//天地一片蒼茫
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define int long long
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << ": " << x << endl
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define lb lower_bound
#define ub upper_bound
#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
int n,m,q,k;
int w[75][75];
int dist[75][75][75];
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin.exceptions(ios::badbit | ios::failbit);
cin>>n>>m;
memset(w,1,sizeof(w));
memset(dist,1,sizeof(dist));
rep(x,0,75) dist[0][x][x]=0,w[x][x]=0;
int a,b,c;
rep(x,0,m){
cin>>a>>b>>c;
a--,b--;
w[a][b]=min(w[a][b],c);
}
rep(i,0,74) rep(x,0,n) rep(y,0,n) rep(z,0,n){
dist[i+1][x][z]=min(dist[i+1][x][z],dist[i][x][y]+w[y][z]);
}
cin>>k>>q;
k=min(k,n);
while (q--){
cin>>a>>b;
a--,b--;
cout<<(dist[k][a][b]>1e9?-1:dist[k][a][b])<<endl;
}
}
