#ifdef Home
#define _GLIBCXX_DEBUG
#endif // Home
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
const int N = 100100;
const int LOGN = 17;
struct MyPQ{
priority_queue < int > pq;
ll sum = 0, y, c;
MyPQ(ll y):y(y) {};
void add(ll x) {
pq.push(x);
sum += x;
for(; sum > y;) {
sum -= pq.top();
pq.pop();
++ c;
}
}
};
vector < pair < int, int > > adj[N];
vector < int > C[N];
int n, m, q, cnt[N][LOGN], depth[N], up[N][LOGN], P_C[N];
void dfs1(int v, int p) {
depth[v] = depth[p] + 1;
up[v][0] = p;
for(int i = 1; i < LOGN; ++ i) {
up[v][i] = up[ up[v][i - 1] ][i - 1];
}
for(auto &[u, w] : adj[v]) {
if(u != p) {
P_C[u] = w;
dfs1(u, v);
}
}
}
ll slow_LCA(ll a, ll b, ll &Y) {
if(depth[a] < depth[b]) {
swap(a, b);
}
MyPQ ans(Y);
for(; depth[a] > depth[b];) {
for(auto &i : C[P_C[a]]) {
ans.add(i);
}
a = up[a][0];
}
for(; a != b;) {
for(auto &i : C[P_C[a]]) {
ans.add(i);
}
for(auto &i : C[P_C[b]]) {
ans.add(i);
}
a = up[a][0];
b = up[b][0];
}
return ans.c;
}
void solve_subtask_1() {
dfs1(1, 1);
ll s, t, X, Y, Z;
for(; q --> 0;) {
cin >> s >> t >> X >> Y;
Z = slow_LCA(s, t, Y);
cout << (X < Z ? -1 : X - Z) << '\n';
}
}
main() {
#ifdef Home
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif // Home
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> q;
for(int u, v, i = 1; i < n; ++ i) {
cin >> u >> v;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
}
for(int p, c; m --> 0;) {
cin >> p >> c;
C[p].push_back(c);
}
if(n <= 2023 && q <= 2023) {
solve_subtask_1();
return 0;
}
}
