#include <bits/stdc++.h>
using namespace std;
#define int long long
#define f first
#define s second
const int N = 1e5 + 69;
const int inf = 1e18;
int n, m, q, p[N], c[N], par[N], timer, tin[N], tout[N];
vector<int> g[N];
vector<tuple<int, int, int>> e;
map<pair<int, int>, vector<int>> cnt;
bool anc(int a, int b) {
return tin[a] <= tin[b] && tout[a] >= tout[b];
}
void dfs(int v, int p) {
par[v] = p;
tin[v] = ++timer;
for (auto u : g[v]) {
if (u == p)
continue;
dfs(u, v);
}
tout[v] = timer;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
cin >> n >> m >> q;
for (int i = 1;i <= n - 1;i++) {
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
e.push_back({a, b, 0});
}
for (int i = 1;i <= m;i++) {
cin >> p[i] >> c[i];
--p[i];
int a, b, w;
tie(a, b, w) = e[p[i]];
if (a > b)
swap(a, b);
cnt[{a, b}].push_back(c[i]);
}
dfs(1, 0);
for (int i = 1;i <= q;i++) {
int s, t, x, y;
cin >> s >> t >> x >> y;
vector<int> gas;
int up = s;
while (!anc(up, t)) {
int x = up, y = par[up];
if (x > y)
swap(x, y);
if (cnt.count({x, y})) {
for (auto u : cnt[{x, y}])
gas.push_back(u);
}
up = par[up];
}
int v = t;
while (v != up) {
int x = v, y = par[v];
if (x > y)
swap(x, y);
if (cnt.count({x, y})) {
for (auto u : cnt[{x, y}])
gas.push_back(u);
}
v = par[v];
}
sort(gas.begin(), gas.end());
int ans = x, sm = 0, m = gas.size();
for (int i = 0;i < m;i++) {
if (sm + gas[i] <= y)
sm += gas[i];
else {
if (m - i <= x)
ans = x - (m - i);
else
ans = -1;
break;
}
}
cout << ans << '\n';
}
}
return 0;
}
