//I wrote this code 4 u <3
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#ifdef LOCAL
#include "algo/debug.h"
#else
#define debug(...) 42
#endif
struct Q {
int l, r, x;
ll y;
int i;
};
const int K = 417;
const int maxN = 100'100;
bool used[maxN];
signed main(int32_t argc, char *argv[]) {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, q;
cin >> n >> m >> q;
vector<vector<pair<int, int>>> g(n);
for (int i = 0; i < n - 1; ++i) {
int u, v;
cin >> u >> v;
--u, --v;
g[u].push_back({v, i});
g[v].push_back({u, i});
}
vector<pair<int, int>> srt;
vector<vector<pair<int, int>>> tmp(n - 1);
for (int i = 0; i < m; ++i) {
int p, x;
cin >> p >> x;
tmp[p - 1].push_back({x, i});
srt.push_back({x, i});
}
sort(srt.begin(), srt.end());
vector<vector<int>> ex(n - 1);
for (int i = 0; i < n - 1; ++i) {
for (auto x : tmp[i]) {
ex[i].push_back(lower_bound(srt.begin(), srt.end(), x) - srt.begin());
}
}
vector<int> tin(n), ord;
auto Dfs = [&](auto&& self, int u, int p) -> void {
tin[u] = (int) ord.size();
for (auto [to, i] : g[u]) {
if (to == p) continue;
for (auto id : ex[i]) ord.push_back(id);
self(self, to, u);
for (auto id : ex[i]) ord.push_back(id);
}
};
Dfs(Dfs, 0, -1);
vector<Q> qry(q);
for (int i = 0; i < q; ++i) {
int u, v, x;
ll y;
cin >> u >> v >> x >> y;
u = tin[u - 1], v = tin[v - 1];
if (u > v) swap(u, v);
qry[i] = {u, v, x, y, i};
}
sort(qry.begin(), qry.end(), [&](auto i, auto j) {
if (i.l / K != j.l / K) return i.l < j.l;
return (bool) ((i.r < j.r) ^ ((i.l / K) & 1));
});
int sz = (m + K - 1) / K;
vector<vector<ll>> bl(sz, vector<ll>(K, 0ll));
vector<ll> sm(sz, 0ll);
vector<int> cnt(sz, 0);
ll s = 0ll;
int c = 0;
auto chk = [&](int i) {
i = ord[i];
int ii = i / K, iii = i % K;
if (!used[i]) {
sm[ii] += srt[i].first;
bl[ii][iii] += srt[i].first;
s += srt[i].first;
cnt[ii]++;
c++;
} else {
sm[ii] -= srt[i].first;
bl[ii][iii] -= srt[i].first;
s -= srt[i].first;
cnt[ii]--;
c--;
}
used[i] ^= 1;
};
vector<int> ans(q);
int cl = 0, cr = 0;
for (auto [l, r, x, y, id] : qry) {
while (cl > l) chk(--cl);
while (cl < l) chk(cl++);
while (cr > r) chk(--cr);
while (cr < r) chk(cr++);
ll cur = s;
for (int i = sz - 1; i > -1; --i) {
if (cur - sm[i] <= y) {
for (int j = K - 1; j > -1 && cur > y; --j) {
if (bl[i][j]) {
x--;
cur -= bl[i][j];
}
}
break;
} else {
x -= cnt[i];
cur -= sm[i];
}
}
ans[id] = max(-1, x);
}
for (auto x : ans) cout << x << '\n';
}
/*
*/
