#include <bits/stdc++.h>
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define uniq(x) x.erase(unique(all(x)), x.end())
#define rall(x) x.rbegin(), x.rend()
#define each(x, v) for(auto &x : v)
#define mp make_pair
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using str = string;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using Node = array<ll, 3>;
const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
void setIO() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
}
int32_t main() {
setIO();
int n, m;
cin >> n >> m;
vector<vector<pii> > graph(n+1);
int mat[n+1][n+1];
memset(mat, 0, sizeof(mat));
for(int i=0; i<m; i++) {
int a, b, w;
cin >> a >> b >> w;
if(mat[a][b] == 0) mat[a][b] = w;
else mat[a][b] = min(mat[a][b], w);
}
for(int i=1; i<=n; i++)
for(int j=1; j<=n; j++)
if(mat[i][j] != 0)
graph[i].pb({ j, mat[i][j] });
int k, q;
cin >> k >> q;
k = min(k, n);
vector<vector<ll> > ans(n+1, vector<ll>(n+1, 1e18));
vector<vector<vector<ll> > > dist(n+1, vector<vector<ll>>(n+1, vector<ll>(k+1, 1e18)));
priority_queue<Node, vector<Node>, greater<Node> > pq;
for(int i=1; i<=n; i++) {
dist[i][i][0] = 0;
bool vis[n+1][k+1];
memset(vis, 0, sizeof(vis));
pq.push({ 0, 0, i });
while(!pq.empty()) {
ll d = pq.top().at(0);
int c = pq.top().at(1);
int u = pq.top().at(2);
pq.pop();
if(vis[u][c]) continue;
vis[u][c] = true;
if(c == k) continue;
for(pii &v : graph[u]) {
if(dist[i][v.first][c+1] > dist[i][u][c] + v.second) {
dist[i][v.first][c+1] = dist[i][u][c] + v.second;
if(vis[v.first][c+1]) continue;
pq.push({ dist[i][v.first][c+1], c+1, v.first });
}
}
}
for(int j=1; j<=n; j++) {
for(int x=0; x<k+1; x++) {
ans[i][j] = min(ans[i][j], dist[i][j][x]);
}
}
}
while(q--) {
int a, b;
cin >> a >> b;
cout << (ans[a][b] == 1e18 ? -1 : ans[a][b]) << '\n';
}
return 0;
}
