#include <bits/stdc++.h>
using namespace std;
template<typename T>
struct Fenwick {
vector<T> f;
Fenwick(int N = 0): f(N) {
}
void add(int x, T v) {
for (; x < int(f.size()); x |= (x + 1)) f[x] += v;
}
T get(int x) {
T ans{};
for (; x >= 0; x = (x & (x + 1)) - 1) ans += f[x];
return ans;
}
};
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int N, M, Q; cin >> N >> M >> Q;
vector<vector<int>> adj(N);
vector<array<int, 2>> E(N - 1);
for (int i = 0; i + 1 < N; ++i) {
cin >> E[i][0] >> E[i][1]; --E[i][0], --E[i][1];
adj[E[i][0]].push_back(E[i][1]);
adj[E[i][1]].push_back(E[i][0]);
}
vector<int> par(N, -1);
vector<int> sz(N);
vector<int> depth(N);
function<void(int)> dfs = [&](int v) {
sz[v] = 1;
for (int u : adj[v]) {
par[u] = v;
adj[u].erase(find(adj[u].begin(), adj[u].end(), v));
depth[u] = depth[v] + 1;
dfs(u);
sz[v] += sz[u];
}
};
dfs(0);
int timer = 0;
vector<int> top(N);
vector<int> tin(N);
vector<int> tout(N);
function<void(int, int)> hld = [&](int v, int t) {
tin[v] = timer++;
top[v] = t;
int nv = -1;
for (int u : adj[v]) {
if (nv == -1 || sz[u] > sz[nv]) nv = u;
}
if (nv >= 0) hld(nv, t);
for (int u : adj[v]) {
if (u != nv) hld(u, u);
}
tout[v] = timer;
};
hld(0, 0);
auto get_lca = [&](int v, int u) {
while (top[v] != top[u]) {
if (depth[top[v]] > depth[top[u]]) {
v = par[top[v]];
} else {
u = par[top[u]];
}
}
return depth[v] <= depth[u] ? v : u;
};
for (int i = 0; i < N - 1; ++i) {
if (depth[E[i][0]] > depth[E[i][1]]) {
swap(E[i][0], E[i][1]);
}
}
vector<pair<int, int>> cpts(M);
for (int i = 0; i < M; ++i) {
int k, c; cin >> k >> c;
cpts[i] = {c, E[k - 1][1]};
}
sort(cpts.begin(), cpts.end());
Fenwick<int> f(N);
for (auto [c, v] : cpts) {
f.add(tin[v], +1);
f.add(tout[v], -1);
}
vector<int> from(Q);
vector<int> to(Q);
vector<int> lca(Q);
vector<int> cnt(Q);
vector<int> gold(Q);
vector<int> ans(Q);
vector<int64_t> silver(Q);
vector<int> lo(Q, 0);
vector<int> hi(Q, M - 1);
for (int q = 0; q < Q; ++q) {
cin >> from[q] >> to[q]; --from[q], --to[q];
lca[q] = get_lca(from[q], to[q]);
cnt[q] = f.get(tin[from[q]]) + f.get(tin[to[q]]) - 2 * f.get(tin[lca[q]]);
cin >> gold[q] >> silver[q];
ans[q] = gold[q] - cnt[q];
}
vector<vector<int>> queries(M);
while (true) {
bool done = true;
for (int q = 0; q < Q; ++q) if (lo[q] <= hi[q]) {
done = false;
int md = (lo[q] + hi[q]) / 2;
queries[md].push_back(q);
}
if (done) break;
Fenwick<int> fcnt(N);
Fenwick<int64_t> fsum(N);
for (int md = 0; md < M; ++md) {
auto [c, v] = cpts[md];
fcnt.add(tin[v], +1);
fcnt.add(tout[v], -1);
fsum.add(tin[v], +c);
fsum.add(tout[v], -c);
for (int q : queries[md]) {
int64_t sum = fsum.get(tin[from[q]]) + fsum.get(tin[to[q]]) - 2 * fsum.get(tin[lca[q]]);
int cnt0 = fcnt.get(tin[from[q]]) + fcnt.get(tin[to[q]]) - 2 * fcnt.get(tin[lca[q]]);
if (sum <= silver[q]) {
lo[q] = md+1;
ans[q] = gold[q] - (cnt[q] - cnt0);
} else {
hi[q] = md-1;
}
}
}
for (int i = 0; i < M; ++i) queries[i].clear();
}
for (int q = 0; q < Q; ++q) {
cout << max(ans[q], -1) << '\n';
}
return 0;
}
