// #pragma GCC target ("avx2")
// #pragma GCC optimize ("O3")
// #pragma GCC optimize ("unroll-loops")
// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
#include <numeric>
#include <stack>
using namespace std;
#define int long long
#define endl "\n"
const int N = 2e3 + 5;
vector<int> adj[N];
map<pair<int, int>, int> edge;
vector<int> E[N];
int par[N];
void dfs(int u, int p){
par[u] = p;
for (auto v : adj[u]){
if (v == p) continue;
dfs(v, u);
}
}
void solve() {
int n, m, q; cin >> n >> m >> q;
for (int i = 1; i < n; i++){
int u, v; cin >> u >> v;
edge[{u, v}] = i;
edge[{v, u}] = i;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 1; i <= m; i++){
int p, c; cin >> p >> c;
E[p].push_back(c);
}
for (int Q = 1; Q <= q; Q++){
int u, v, g, s;
cin >> u >> v >> g >> s;
dfs(u, 0);
int x = v;
vector<int> cost;
while (x != u){
for (auto j : E[edge[{x, par[x]}]]) cost.push_back(j);
x = par[x];
}
sort(cost.begin(), cost.end());
int use = cost.size();
for (auto i : cost){
if (s - i >= 0){
s -= i;
use--;
}
}
if (use > g) cout << -1 << endl;
else cout << g - use << endl;
}
return;
}
signed main() {
// freopen("", "r", stdin);
// freopen("", "w", stdout);
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
cout << setprecision(9);
srand(time(0));
int tc = 1;
// cin >> tc;
while (tc--) {
solve();
}
return 0;
}
