#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int lg(unsigned long long i) { return i ? __builtin_clzll(1) - __builtin_clzll(i) : -1; }
struct BIT {
vector<ll> tree;
BIT(int n) { tree = vector<ll>(n + 1); }
ll sum(int k) { ll s = 0; while(k >= 1) s += tree[k], k -= k&-k; return s; }
void add(int k, ll x) { while (k < (int)tree.size()) tree[k] += x, k += k&-k; }
int lb(ll x) {
ll s = 0, p = 0;
for(int i = lg(tree.size()); i >= 0; i--)
if(p + (1 << i) < tree.size() && s + tree[p + (1 << i)] <= x)
p += (1 << i), s += tree[p];
return p;
}
};
struct Edge {
int a, b;
vector<int> c;
};
struct Query {
int S, E, i;
ll s;
};
const int BS = 450;
int main() {
ios::sync_with_stdio(false), cin.tie(nullptr);
int N, M, Q;
cin >> N >> M >> Q;
vector<Edge> edge(N - 1);
vector<vector<int>> inc(N);
for(int i = 0; i < N - 1; i++) {
cin >> edge[i].a >> edge[i].b;
edge[i].a--, edge[i].b--;
inc[edge[i].a].push_back(i);
inc[edge[i].b].push_back(i);
}
vector<pair<ll, int>> cp(M);
for(int i = 0; i < M; i++) {
cin >> cp[i].second >> cp[i].first;
cp[i].second--;
}
sort(cp.begin(), cp.end());
for(int i = 0; i < M; i++) {
edge[cp[i].second].c.push_back(i);
}
vector<int> in(N);
vector<int> o;
function<void(int, int)> dfs = [&] (int s, int e) {
in[s] = o.size();
for(int ei : inc[s]) {
int u = (edge[ei].a == s) ? edge[ei].b : edge[ei].a;
if(u != e) {
for(int c : edge[ei].c) o.push_back(c);
dfs(u, s);
for(int c : edge[ei].c) o.push_back(c);
}
}
};
dfs(0, -1);
vector<Query> queries(Q);
vector<int> gold(Q);
for(int i = 0; i < Q; i++) {
int a, b;
cin >> a >> b >> gold[i] >> queries[i].s;
a--, b--;
if(in[a] > in[b]) swap(a, b);
queries[i].S = in[a];
queries[i].E = in[b];
queries[i].i = i;
}
sort(queries.begin(), queries.end(), [&] (Query a, Query b) {
return (a.S / BS == b.S / BS) ? (a.E < b.E) : (a.S / BS < b.S / BS);
});
vector<int> ans(Q);
vector<int> active(M);
BIT smbit(M);
BIT actbit(M);
int totalact = 0;
auto toggle = [&] (int x) {
if(active[x]) {
actbit.add(x + 1, -1);
smbit.add(x + 1, -cp[x].first);
totalact--;
} else {
actbit.add(x + 1, 1);
smbit.add(x + 1, cp[x].first);
totalact++;
}
active[x] ^= 1;
};
int L = 0, R = 0;
for(int i = 0; i < Q; i++) {
while(L < queries[i].S) {
toggle(o[L++]);
}
while(R < queries[i].E) {
toggle(o[R++]);
}
while(L > queries[i].S) {
toggle(o[--L]);
}
while(R > queries[i].E) {
toggle(o[--R]);
}
ans[queries[i].i] = totalact - actbit.sum(smbit.lb(queries[i].s));
}
for(int i = 0; i < Q; i++) {
if(gold[i] < ans[i]) cout << -1 << '\n';
else cout << gold[i] - ans[i] << '\n';
}
}
