#include <bits/stdc++.h>
#define ff first
#define ss second
#define sz size()
#define pb push_back
using namespace std;
typedef long long ll;
const int N = 2005;
// const int mod = 1e9+7;
// ll bigmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll n, m, q, l, r;
vector <ll> v[N], vv;
map <ll, bool> mm;
ll kak[N], san[N][N], p[N], c[N], s, t, gold, silver;
void dfs(int x, int par) {
kak[x] = par;
for (auto i : v[x]) {
if (i != par) {
dfs (i, x);
}
}
}
int main() {
// ios::sync_with_stdio(false);
// cin.tie(0), cout.tie(0);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
// clock_t tStart = clock();
// printf("Time taken: %.2fs\n", (double)(clock() - tStart)/CLOCKS_PER_SEC);
cin >> n >> m >> q;
for (int i = 1; i < n; ++i) {
cin >> l >> r;
v[l].pb (r);
v[r].pb (l);
san[l][r] = i;
san[r][l] = i;
// dan[i].ff = l;
// dan[i].ss = r;
}
for (int i = 1; i <= m; ++i) {
cin >> p[i] >> c[i];
}
while ( q-- ) {
cin >> s >> t >> gold >> silver;
dfs (s, -1);
mm.clear();
vv.clear();
while (kak[t] != -1) {
mm[san[t][kak[t]]] = 1;
t = kak[t];
}
for (int i = 1; i <= m; ++i) {
if (mm[p[i]]) {
vv.pb (c[i]);
}
}
sort (vv.begin(), vv.end());
for (auto i : vv) {
if (silver >= i) {
silver -= i;
}
else {
gold--;
}
}
if (gold < 0) {
cout << "-1" << endl;
}
else cout << gold << endl;
}
}
/*
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*/
