#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N, M, Q;
cin >> N >> M >> Q;
vector<pair<int, int>> edges(N - 1);
vector<vector<pair<int, int>>> adj(N);
for (int i = 0; i < N - 1; i++) {
int x, y;
cin >> x >> y;
x--, y--;
edges[i] = {x, y};
adj[x].emplace_back(y, i);
adj[y].emplace_back(x, i);
}
vector<int> P(M), C(M);
vector<vector<int>> c(N - 1);
for (int i = 0; i < M; i++) {
cin >> P[i] >> C[i];
P[i]--;
c[P[i]].push_back(C[i]);
}
if (C == vector(M, C[0])) {
vector<int> cnt(N - 1);
for (int i = 0; i < M; i++) {
cnt[P[i]]++;
}
vector<int> f(N), dep(N);
vector par(N, vector<int>(20, -1));
auto dfs = [&](auto dfs, int x) -> void {
for (int i = 0; i < 19 && par[x][i] != -1; i++) {
par[x][i + 1] = par[par[x][i]][i];
}
for (auto [y, z] : adj[x]) {
if (y != par[x][0]) {
dep[y] = dep[x] + 1;
f[y] = f[x] + cnt[z];
par[y][0] = x;
dfs(dfs, y);
}
}
};
dfs(dfs, 0);
auto lca = [&](int x, int y) {
if (dep[x] < dep[y]) {
swap(x, y);
}
for (int i = 0; i < 20; i++) {
if ((dep[x] - dep[y]) >> i & 1) {
x = par[x][i];
}
}
if (x == y) {
return x;
}
for (int i = 19; i >= 0; i--) {
if (par[x][i] != par[y][i]) {
x = par[x][i];
y = par[y][i];
}
}
return par[x][0];
};
while (Q--) {
int S, T, X; ll Y;
cin >> S >> T >> X >> Y;
S--, T--;
int k = f[S] + f[T] - 2 * f[lca(S, T)];
cout << max(-1LL, X - max(0LL, k - Y / C[0])) << "\n";
}
return 0;
}
while (Q--) {
int S, T, X; ll Y;
cin >> S >> T >> X >> Y;
S--, T--;
vector<int> p(N, -1);
queue<int> q;
p[S] = S;
q.push(S);
while (!q.empty()) {
int x = q.front();
q.pop();
for (auto [y, z] : adj[x]) {
if (p[y] == -1) {
p[y] = z;
q.push(y);
}
}
}
priority_queue<int, vector<int>, greater<int>> pq;
while (T != S) {
for (int v : c[p[T]]) {
pq.push(v);
}
auto [x, y] = edges[p[T]];
T ^= x ^ y;
}
while (!pq.empty() && pq.top() <= Y) {
Y -= pq.top();
pq.pop();
}
X -= pq.size();
X = max(X, -1);
cout << X << "\n";
}
return 6/22;
}
