#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);
}
int s,t,x,y;
vector<int> pr(n+1);
function<void(int,int)> dfs = [&](int w,int p){
pr[w] = p;
for(int to : g[w]){
if(to != p){
dfs(to,w);
}
}
};
while(q--){
cin >> s >> t >> x >> y;
dfs(s,0);
vector<int> ansv;
while(t != s){
for(int i : dis[{t,pr[t]}]) ansv.pb(i);
t = pr[t];
}
sort(all(ansv));
for(int i : ansv){
if(i > y) x--;
else y -= i;
}
if(x >= 0) cout << x << '\n';
else cout << "-1\n";
}
}else{
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>,int> dis;
int us;
for(int i = 0; i < m; i++){
int a,b;
cin >> a >> b;
us = b;
dis[{u[a],v[a]}] += b;
dis[{v[a],u[a]}] += b;
}
vector<int> dist(n+1),tin(n+1),tout(n+1);
vector<vector<int> > up(20,vector<int>(n+1));
int timer = 0;
function<void(int, int, int)> dfs = [&](int w, int pr, int d) {
dist[w] = d;
tin[w] = ++timer;
up[0][w] = pr;
for (int i = 1; i <= 17; i++) {
up[i][w] = up[i - 1][up[i - 1][w]];
}
for (int to : g[w]) {
if (to != pr) dfs(to, w, d + dis[{w,to}]);
}
tout[w] = timer;
};
function<bool(int,int)> upper = [&](int a, int b) {
return tin[a] <= tin[b] && tout[a] >= tout[b];
};
function<int(int,int)> lca = [&](int a, int b) {
if (upper(a, b)) return a;
if (upper(b, a)) return b;
for (int i = 17; i >= 0; i--) {
if (!upper(up[i][a], b)) {
a = up[i][a];
}
}
return up[0][a];
};
dfs(1,0,0);
while(q--){
int s,t,x,y;
cin >> s >> t >> x >> y;
int cost = dist[s] + dist[t] - dist[ lca(s,t) ] * 2;
cost /= us;
cost -= y / us;
x -= max(0ll,cost);
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();
}
}
