#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define x first
#define y second
#define ii pair<ll,ll>
const ll inf=1e16+7;
vector<vector<ii> >a;
ll n,m;
struct node
{
ll x,used,value;
node(ll _value=0,ll _x=0,ll _used=0)
{
x=_x,used=_used,value=_value;
}
};
bool minimize(ll &a,ll b)
{
if(a>b)
{
a=b;
return true;
}
return false;
}
int main()
{
//freopen("test.inp","r",stdin);
//freopen("test.out","w",stdout);
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n>>m;
a.resize(n+7);
for(ll i=1;i<=m;i++)
{
ll x,y,value;
cin>>x>>y>>value;
a[x].push_back({y,value});
}
ll q,k;
cin>>k>>q;
vector<vector<ll> >dp(n+1,vector<ll>(min(k+1,n),inf));
while(q--)
{
ll node_x,node_y;
cin>>node_x>>node_y;
for(ll i=0;i<=min(k,n-1);i++)
{
for(ll node=1;node<=n;node++)dp[node][i]=inf;
}
dp[node_x][0]=0;
queue<node>q;
q.push({0,node_x,0});
while(!q.empty())
{
ll value=q.front().value;
ll x=q.front().x;
ll used=q.front().used;
q.pop();
if(used==min(k,n-1))continue;
if(dp[x][used]!=value)continue;
for(ii u:a[x])
{
ll node=u.x;
ll cost=u.y;
if(minimize(dp[node][used+1],dp[x][used]+cost))
{
q.push({dp[node][used+1],node,used+1});
}
}
}
ll ans=inf;
for(ll i=0;i<=min(k,n-1);i++)ans=min(ans,dp[node_y][i]);
cout<<(ans==inf?-1:ans)<<endl;;
}
}
