#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define all(c) c.begin(), c.end()
#define endl "\n"
const double PI=3.141592653589;
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define dbg(x...) cerr << "LINE(" << __LINE__ << ") -> " <<"[" << #x << "] = ["; _print(x)
#else
#define dbg(x...)
#endif
int n,m,q;
vector<vector<int>>adj, up,tax;
vector<int>par,dist;
void comp(int u, int p){
for(int v : adj[u]){
if(v==p)continue;
par[v] = u;
dist[v] = dist[u]+1;
up[v][0] = u;
for(int j = 1;j<=20;++j)up[v][j] = up[up[v][j-1]][j-1];
comp(v,u);
}
}
int lca(int u, int v){
if(dist[v] > dist[u])swap(v,u);
int k = dist[u]-dist[v];
for(int j = 0;j<=20;++j){
if(k&(1ll<<j))u = up[u][j];
}
if(u==v)return u;
for(int j = 20;j>=0;--j){
if(up[u][j] != up[v][j])u = up[u][j], v = up[v][j];
}
return up[v][0];
}
void solve()
{
cin >> n >> m >> q;
adj.resize(n+1);
up = vector<vector<int>>(n+1, vector<int>(21));
vector<pair<int,int>>edges = {{0,0}};
dist.resize(n+1);
tax.resize(n+1);
par.resize(n+1);
for(int i = 1;i<n;++i){
int u,v;
cin >> u >> v;
edges.pb({u,v});
adj[u].pb(v);
adj[v].pb(u);
}
comp(1,-1);
for(int i = 1;i<=m;++i){
int p,c;
cin >> p >> c;
int u = edges[p].first, v = edges[p].second;
if(par[u] == v)swap(v,u);
// par[v] = u
tax[v].pb(c);
}
while(q--){
int u,v,g,s;
cin >> u >> v >> g >> s;
int l = lca(u,v);
vector<int>res;
while(u!=l){
for(auto x : tax[u])res.pb(x);
u = par[u];
}
while(v!=l){
for(auto x : tax[v])res.pb(x);
v = par[v];
}
sort(all(res));
bool got = 0;
for(int i = 0;i<res.size();++i){
if(s>=res[i])s-=res[i];
else{
int need = res.size()-i;
int val = g-need;
if(val < 0)val = -1;
cout << val << endl;
got = 1;
break;
}
}
if(!got)cout << g << endl;
}
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
int T=1;
for(int i = 1;i<=T;++i)
{
// cout << "Case #" << i << ": ";
solve();
}
}
