/*input
4 7
1 2 1
1 4 10
2 3 1
2 4 5
3 2 2
3 4 1
4 3 2
3 3
1 4
4 2
3 3
*/
#include<bits/stdc++.h>
using namespace std;
//#pragma GCC target("avx2")
//order_of_key #of elements less than x
// find_by_order kth element
#define ll long long
#define ld long double
#define pii pair<ld,ld>
#define f first
#define s second
#define pb push_back
#define REP(i,n) for(int i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define FILL(n,x) memset(n,x,sizeof(n))
#define ALL(_a) _a.begin(),_a.end()
#define sz(x) (int)x.size()
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()),c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
const ll maxn=70+5;
const ll maxlg=__lg(maxn)+2;
const ll INF64=4e18;
const int INF=0x3f3f3f3f;
const ll MOD=1e9+7;
const ld PI=acos(-1.0);
const ld eps=1e-8;
#define lowb(x) x&(-x)
#define MNTO(x,y) x=min(x,(__typeof__(x))y)
#define MXTO(x,y) x=max(x,(__typeof__(x))y)
template<typename T1,typename T2>
ostream& operator<<(ostream& out,pair<T1,T2> P){
out<<P.f<<' '<<P.s;
return out;
}
template<typename T>
ostream& operator<<(ostream& out,vector<T> V){
REP(i,sz(V)) out<<(V[i])<<((i!=sz(V)-1)?" ":"\n");
return out;
}
ll mult(ll a,ll b){
return a*b%MOD;
}
ll mypow(ll a,ll b){
a%=MOD;
if(a==0) return 0;
if(b<=0) return 1;
ll res=1LL;
while(b){
if(b&1) res=(res*a)%MOD;
a=(a*a)%MOD;
b>>=1;
}
return res;
}
int dist[maxn][maxn][maxn];
int32_t main(){
ios::sync_with_stdio(false),cin.tie(0);
int n,m;
cin>>n>>m;
REP(i,n+1) REP(a,n) REP(b,n) dist[i][a][b]=INF;
REP(i,n) dist[0][i][i]=0;
REP(i,m){
int a,b,c;
cin>>a>>b>>c;
--a,--b;
MNTO(dist[1][a][b],c);
}
int K,q;
cin>>K>>q;
MNTO(K,n-1);
REP1(x,K){
REP(k,n){
REP(a,n){
REP(b,n){
MNTO(dist[x][a][b],dist[x-1][a][k]+dist[1][k][b]);
}
}
}
}
while(q--){
int a,b;
cin>>a>>b;
--a,--b;
int ans=dist[K][a][b];
REP(j,K+1) MNTO(ans,dist[j][a][b]);
if(ans==INF) ans=-1;
cout<<ans<<'\n';
}
}
