#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
#define sz(x) (int) x.size()
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef pair <int, int> ii;
const int N = 2e5 + 1;
const int mod = 998244353;
int n, m, q;
int p[N], c[N], mark[N];
vector <int> path, save;
vector <ii> ed[N];
void dfs(int u, int par, int k) {
if (u == k)
save = path;
for(auto v: ed[u]) {
if (v.f == par) continue;
path.push_back(v.s);
dfs(v.f, u, k);
path.pop_back();
}
}
void sub1() {
while (q--) {
int s, t, x; ll y;
cin >> s >> t >> x >> y;
dfs(s, s, t);
for(auto x: save)
mark[x] = true;
priority_queue <int, vector <int>, greater <int>> pq;
for(int i = 1; i <= m; i++) {
if (mark[p[i]]) {
pq.push(c[i]);
}
}
while (sz(pq) && y >= pq.top()) y -= pq.top(), pq.pop();
cout << (x >= sz(pq) ? x - sz(pq) : -1) << "\n";
for(auto x: save)
mark[x] = false;
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> m >> q;
for(int u, v, i = 1; i < n; i++) {
cin >> u >> v;
ed[u].push_back({v, i});
ed[v].push_back({u, i});
}
for(int i = 1; i <= m; i++)
cin >> p[i] >> c[i];
if (n <= 2000 && m <= 2000 && q <= 2000) {
sub1();
}
return 0;
}
