#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
ll n,m,q;
if(!(cin >> n >> m >> q)) return 0;
vector<pair<int,int>> edges; edges.reserve(max(0LL, n-1));
vector<vector<pair<int,int>>> adj(n); // (neighbor, edge_index)
for (int i = 0; i < n-1; ++i){
int a,b; cin >> a >> b; --a; --b;
edges.emplace_back(a,b);
adj[a].push_back({b,i});
adj[b].push_back({a,i});
}
vector<vector<ll>> price_per_edge(max(0ll, n-1));
for (int i = 0; i < m; ++i){
int eidx; ll val; cin >> eidx >> val; --eidx;
if (eidx >= 0 && eidx < (int)price_per_edge.size()){
price_per_edge[eidx].push_back(val);
}
// if invalid index in input, we ignore to avoid crash
}
// BFS from root 0 to compute parent (0-based), depth and parent_edge
vector<int> parent(n, -1);
vector<int> parent_edge(n, -1);
vector<int> depth(n, 0);
queue<int> qu;
qu.push(0);
parent[0] = -1;
depth[0] = 0;
while(!qu.empty()){
int v = qu.front(); qu.pop();
for (auto [to, eidx] : adj[v]){
if (to == parent[v]) continue;
parent[to] = v;
parent_edge[to] = eidx;
depth[to] = depth[v] + 1;
qu.push(to);
}
}
// Answer queries: gather all prices along path (using parent pointers), sort, greedy take by y
while (q--){
int a,b; ll x,y;
cin >> a >> b >> x >> y; --a; --b;
if (a < 0 || a >= n || b < 0 || b >= n){
cout << "-1\n";
continue;
}
vector<ll> collected;
collected.clear();
int u = a, v = b;
// lift deeper one using parent pointers, collecting edge indices
while (depth[u] > depth[v]){
int e = parent_edge[u];
if (e >= 0) {
for (ll val : price_per_edge[e]) collected.push_back(val);
}
u = parent[u];
}
while (depth[v] > depth[u]){
int e = parent_edge[v];
if (e >= 0) {
for (ll val : price_per_edge[e]) collected.push_back(val);
}
v = parent[v];
}
// now same depth, climb both until meet
while (u != v){
int eu = parent_edge[u];
int ev = parent_edge[v];
if (eu >= 0){
for (ll val : price_per_edge[eu]) collected.push_back(val);
}
if (ev >= 0){
for (ll val : price_per_edge[ev]) collected.push_back(val);
}
u = parent[u];
v = parent[v];
}
// sort collected prices ascending and greedily spend y
sort(collected.begin(), collected.end());
ll i = 0;
while (i < (ll)collected.size() && y >= collected[i]){
y -= collected[i];
++i;
}
ll remaining = (ll)collected.size() - i;
if (remaining > x){
cout << "-1\n";
} else {
cout << (x - remaining) << "\n";
}
}
return 0;
}
