#include <bits/stdc++.h> using namespace std; #define ll long long #define pii pair<int,int> #define fi first #define se second const int N = 1e6 + 5; int n, m, q; vector<pii> g[N]; vector<int> c[N]; int main() { ios::sync_with_stdio(0); cin.tie(0); cin >> n >> m >> q; for (int i = 1; i <= n - 1; i++) { int u, v; cin >> u >> v; g[u].push_back({v, i}); g[v].push_back({u, i}); } for (int i = 0; i < m; i++) { int p; ll w; cin >> p >> w; c[p].push_back(w); } while (q--) { int s, t; ll x, y; cin >> s >> t >> x >> y; vector<int> par(n + 1, -1), pe(n + 1, -1); stack<int> st; st.push(s); par[s] = s; while (!st.empty()) { int u = st.top(); st.pop(); if (u == t) break; for (auto e : g[u]) { int v = e.first, id = e.second; if (par[v] == -1) { par[v] = u; pe[v] = id; st.push(v); } } } if (par[t] == -1) { cout << -1 << "\n"; continue; } vector<ll> a; int cur = t; while (cur != s) { for (ll w : c[pe[cur]]) a.push_back(w); cur = par[cur]; } sort(a.begin(), a.end()); ll sy = 0; int cnt = 0; for (ll w : a) { if (sy + w <= y) { sy += w; cnt++; } else break; } ll res = (ll)(a.size() - cnt); if (res <= x) cout << x - res << '\n'; else cout << -1 << '\n'; } }