#include <iostream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
const int LOG = 18;
template <typename T>
struct binary_indexed_tree{
int N;
std::vector<T> BIT;
binary_indexed_tree(int N): N(N), BIT(N + 1, 0){
}
void add(int i, T x){
i++;
while (i <= N){
BIT[i] += x;
i += i & -i;
}
}
T sum(int i){
T ans = 0;
while (i > 0){
ans += BIT[i];
i -= i & -i;
}
return ans;
}
};
int main(){
int N, M, Q;
std::cin >> N >> M >> Q;
std::vector<int> A(N - 1), B(N - 1);
for (int i = 0; i < N - 1; i++){
std::cin >> A[i] >> B[i];
A[i]--;
B[i]--;
}
std::vector<int> P(M), C(M);
for (int i = 0; i < M; i++){
std::cin >> P[i] >> C[i];
P[i]--;
}
std::vector<int> S(Q), T(Q);
std::vector<int> X(Q);
std::vector<long long> Y(Q);
for (int i = 0; i < Q; i++){
std::cin >> S[i] >> T[i] >> X[i] >> Y[i];
S[i]--;
T[i]--;
}
std::vector<std::vector<int>> E(N);
for (int i = 0; i < N - 1; i++){
E[A[i]].push_back(B[i]);
E[B[i]].push_back(A[i]);
}
std::vector<int> p(N, -1);
std::vector<std::vector<int>> c(N);
std::vector<int> d(N, 0);
std::queue<int> q;
q.push(0);
while (!q.empty()){
int v = q.front();
q.pop();
for (int w : E[v]){
if (w != p[v]){
p[w] = v;
c[v].push_back(w);
d[w] = d[v] + 1;
q.push(w);
}
}
}
for (int i = 0; i < N - 1; i++){
if (B[i] == p[A[i]]){
std::swap(A[i], B[i]);
}
}
std::vector<std::vector<int>> pp(LOG, std::vector<int>(N, -1));
pp[0] = p;
for (int i = 0; i < LOG - 1; i++){
for (int j = 0; j < N; j++){
if (pp[i][j] != -1){
pp[i + 1][j] = pp[i][pp[i][j]];
}
}
}
std::vector<int> L(Q);
for (int i = 0; i < Q; i++){
int u = S[i], v = T[i];
if (d[u] > d[v]){
std::swap(u, v);
}
for (int j = 0; j < LOG; j++){
if (((d[v] - d[u]) >> j & 1) == 1){
v = pp[j][v];
}
}
if (u == v){
L[i] = u;
} else {
for (int j = LOG - 1; j >= 0; j--){
if (pp[j][u] != pp[j][v]){
u = pp[j][u];
v = pp[j][v];
}
}
L[i] = p[u];
}
}
std::vector<int> in(N), out(N);
int t = 0;
auto dfs = [&](auto dfs, int v = 0) -> void {
if (v != 0){
in[v] = t;
t++;
}
for (int w : c[v]){
dfs(dfs, w);
}
if (v != 0){
out[v] = t;
t++;
}
};
dfs(dfs);
in[0] = -1;
std::vector<std::pair<int, int>> D(M);
for (int i = 0; i < M; i++){
D[i] = std::make_pair(C[i], P[i]);
}
std::sort(D.begin(), D.end());
std::vector<int> tv(Q, -1), fv(Q, M + 1);
std::vector<int> cnt(Q);
while (true){
bool ok = true;
std::vector<std::vector<int>> id(M + 1);
for (int i = 0; i < Q; i++){
if (fv[i] - tv[i] > 1){
ok = false;
id[(tv[i] + fv[i]) / 2].push_back(i);
}
}
if (ok){
break;
}
binary_indexed_tree<int> BIT1(N * 2 - 2);
binary_indexed_tree<long long> BIT2(N * 2 - 2);
for (int i = 0; i < M; i++){
BIT1.add(in[B[P[i]]], 1);
BIT1.add(out[B[P[i]]], -1);
}
for (int i = 0; i <= M; i++){
for (int j : id[i]){
long long s = BIT2.sum(in[S[j]] + 1) + BIT2.sum(in[T[j]] + 1) - BIT2.sum(in[L[j]] + 1) * 2;
if (s <= Y[j]){
cnt[j] = BIT1.sum(in[S[j]] + 1) + BIT1.sum(in[T[j]] + 1) - BIT1.sum(in[L[j]] + 1) * 2;
tv[j] = i;
} else {
fv[j] = i;
}
}
if (i < M){
int x = D[i].first;
int e = D[i].second;
BIT1.add(in[B[e]], -1);
BIT1.add(out[B[e]], 1);
BIT2.add(in[B[e]], x);
BIT2.add(out[B[e]], -x);
}
}
}
for (int i = 0; i < Q; i++){
std::cout << std::max(X[i] - cnt[i], -1) << "\n";
}
}
