/*
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
*/
#include<bits/stdc++.h>
#define int long long
using namespace std;
#define all(x) x.begin(), x.end()
#define len(x) ll(x.size())
#define eb emplace_back
#define PI 3.14159265359
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define MIN(v) *min_element(all(v))
#define MAX(v) *max_element(all(v))
#define BIT(x,i) (1&((x)>>(i)))
#define MASK(x) (1LL<<(x))
#define task "tnc"
typedef long long ll;
const ll INF=1e18;
const int maxn=1e6+5;
const int mod=1e9+7;
const int mo=998244353;
using pi=pair<ll,ll>;
using vi=vector<ll>;
using pii=pair<pair<ll,ll>,ll>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n,m;
int f[71][71][71];
int dis[71][71];
signed main()
{
cin.tie(0),cout.tie(0)->sync_with_stdio(0);
//freopen(task".inp" , "r" , stdin);
//freopen(task".out" , "w" , stdout);
cin>>n>>m;
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
dis[i][j]=INF;
}
}
for(int i=1;i<=m;i++){
int a,b,t;
cin>>a>>b>>t;
dis[a][b]=min(dis[a][b],t);
}
int k,q;
cin>>k>>q;
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
if(i==j)f[i][j][0]=0;
else f[i][j][0]=INF;
}
}
for(int i=1;i<=min(n,k);i++){
for(int j=1;j<=n;j++){
for(int z=1;z<=n;z++){
f[j][z][i]=f[j][z][i-1];
}
}
for(int j=1;j<=n;j++){
for(int z=1;z<=n;z++){
for(int k=1;k<=n;k++){
f[j][k][i]=min(f[j][z][i-1]+dis[z][k],f[j][k][i]);
}
}
}
}
while(q--){
int c,d;
cin>>c>>d;
if(f[c][d][min(n,k)]==INF){
cout<<-1<<"\n";
}
else{
cout<<f[c][d][min(n,k)]<<"\n";
}
}
return 0;
}
