#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define int long long
#define pb push_back
#define ff first
#define ss second
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define ordered_set tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update>
#define ordered_multiset tree<type1, null_type, less_equal<type1>, rb_tree_tag, tree_order_statistics_node_update>;
using namespace std;
using namespace __gnu_pbds;
const int mod = 998244353;
const long double PI = acos(-1.0);
const double epsilon = 1e-6;
const int N = 1e5 + 5;
void solve(){
int n,m,q;
cin >> n >> m >> q;
if(n <= 2000 && m <= 2000 && q <= 2000){
vector<int> u(n+1),v(n+1);
vector<vector<int> > g(n+1);
for(int i = 1; i < n; i++){
cin >> u[i] >> v[i];
g[u[i]].pb(v[i]);
g[v[i]].pb(u[i]);
}
map<pair<int,int>,vector<int> > dis;
for(int i = 0; i < m; i++){
int a,b;
cin >> a >> b;
dis[{u[a],v[a]}].pb(b);
dis[{v[a],u[a]}].pb(b);
}
vector<int> ansv;
int s,t,x,y;
function<void(int,int,vector<int>)> dfs = [&](int w,int p,vector<int> us){
for(auto i : dis[{p,w}]){
us.pb(i);
}
if(w == t){
ansv = us;
return;
}
for(int to : g[w]){
if(to != p){
dfs(to,w,us);
}
}
};
while(q--){
cin >> s >> t >> x >> y;
dfs(s,0,{});
sort(all(ansv));
for(int i : ansv){
if(i > y) x--;
else y -= i;
}
if(x >= 0) cout << x << '\n';
else cout << "-1\n";
}
}
}
main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
solve();
}
}
