#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define REPD(i, n) for (int i = 👎 - 1; i >= 0; --i)
#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
/*
Phu Trong from Nguyen Tat Thanh High School for gifted student
*/
template <class X, class Y>
bool minimize(X &x, const Y &y){
X eps = 1e-9;
if (x > y + eps) {x = y; return 1;}
return 0;
}
template <class X, class Y>
bool maximize(X &x, const Y &y){
X eps = 1e-9;
if (x + eps < y) {x = y; return 1;}
return 0;
}
#define MAX_NODE 71
#define MAX_EDGE 1000005
int numNode, numEdge, numQuery, maxUse;
int dp[MAX_NODE][MAX_NODE][MAX_NODE];
int cost[MAX_NODE][MAX_NODE];
void process(void){
cin >> numNode >> numEdge;
memset(cost, 0x3f, sizeof(cost));
for (int i = 1; i <= numEdge; ++i){
int u, v, w; cin >> u >> v >> w;
minimize(cost[u][v], w);
}
cin >> maxUse >> numQuery;
memset(dp, 0x3f, sizeof dp);
for (int i = 1; i <= numNode; ++i){
dp[0][i][i] = 0;
}
for (int d = 0; d < numNode; ++d){
FOR(u, 1, numNode) FOR(v, 1, numNode) if(dp[d][u][v] < LINF){
FOR(x, 1, numNode) minimize(dp[d + 1][u][x], dp[d][u][v] + cost[v][x]);
}
}
maxUse = min(maxUse, numNode);
for (int i = 1; i <= numQuery; ++i){
int u, v; cin >> u >> v;
int ans = LINF;
for (int d = 0; d <= maxUse; ++d) minimize(ans, dp[d][u][v]);
cout << (ans >= INF ? -1 : ans) << '\n';
}
}
signed main(){
#define name "Whisper"
cin.tie(nullptr) -> sync_with_stdio(false);
//freopen(name".inp", "r", stdin);
//freopen(name".out", "w", stdout);
process();
}
