#include <bits/stdc++.h>
using namespace std;
#define ll long long
const ll mmod = 998244353;
#define vl vector<long long>
#define vll vector<vector<long long>>
#define pl pair<long long, long long>
#define vb vector<bool>
bool find_path(ll x, ll p, ll y, vll& graf, map<pl,vl>& prices, vl& res){
if (x == y){
return true;
}
for (ll v : graf[x]){
if (v != p){
bool end = find_path(v, x, y, graf, prices, res);
if (end){
for (ll r : prices[{x, v}]){
res.push_back(r);
}
return true;
}
}
}
return false;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
ll n,m,q;
cin >> n >> m >> q;
vll graf (n);
map<pl,vl> price;
vector<pl> edges;
for (ll i = 0; i < n-1; i++){
ll a,b;
cin >> a >> b;
a--; b--;
graf[a].push_back(b);
graf[b].push_back(a);
edges.push_back({a,b});
}
for (ll i = 0; i < m; i++){
ll a,b;
cin >>a >>b;
a--;
price[edges[a]].push_back(b);
price[{edges[a].second,edges[a].first}].push_back(b);
}
while (q--){
ll a,b,x,y;
cin >>a >> b >> x >> y;
a--;b--;
vl res;
res.clear();
find_path(a, -1, b, graf, price, res);
sort(res.begin(), res.end());
ll i = 0;
while (i < res.size()&& y >= res[i]){
y -= res[i];
i++;
}
if (res.size()-i > x){
cout << "-1\n";
}
else{
cout << x - (res.size()-i) << "\n";
}
}
return 0;
}
