/**
* author: wxhtzdy
* created: 19.03.2023 07:01:27
**/
#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
const int L = 18;
const int M = N * 32;
const int inf = (int) 1e9 + 1;
int rt[N], cs[N], tsz, ls[M], rs[M], cnt[M];
long long sum[M];
vector<int> g[N];
int pr[N][L];
int x[N], y[N], dep[N];
void Modify(int& v, int p, int l, int r, int x, int d) {
v = ++tsz;
ls[v] = ls[p];
rs[v] = rs[p];
cnt[v] = cnt[p] + d;
sum[v] = sum[p] + x * d;
if (l == r) {
return;
}
int mid = l + r >> 1;
if (x <= mid) {
Modify(ls[v], ls[p], l, mid, x, d);
} else {
Modify(rs[v], rs[p], mid + 1, r, x, d);
}
}
int GetCnt(int v, int l, int r, int ql, int qr) {
if (!v || l > r || ql > qr || l > qr || r < ql) {
return 0;
}
if (ql <= l && r <= qr) {
return cnt[v];
}
int mid = l + r >> 1;
return GetCnt(ls[v], l, mid, ql, qr) + GetCnt(rs[v], mid + 1, r, ql, qr);
}
long long GetSum(int v, int l, int r, int ql, int qr) {
if (!v || l > r || ql > qr || l > qr || r < ql) {
return 0LL;
}
if (ql <= l && r <= qr) {
return sum[v];
}
int mid = l + r >> 1;
return GetSum(ls[v], l, mid, ql, qr) + GetSum(rs[v], mid + 1, r, ql, qr);
}
int FindFirst(int v0, int v1, int v2, int l, int r, int x) {
if (l == r) {
return l;
}
int mid = l + r >> 1;
int L = cnt[ls[v0]] + cnt[ls[v1]] - 2 * cnt[ls[v2]];
if (L >= x) {
return FindFirst(ls[v0], ls[v1], ls[v2], l, mid, x);
} else {
return FindFirst(rs[v0], rs[v1], rs[v2], mid + 1, r, x - L);
}
}
void Go(int v, int pv) {
for (int u : g[v]) {
if (u == pv) {
continue;
}
dep[u] = dep[v] + 1;
Go(u, v);
}
}
vector<int> qs[N];
void Dfs(int v, int pv) {
pr[v][0] = pv;
for (int j = 1; j < L; j++) {
pr[v][j] = pr[pr[v][j - 1]][j - 1];
}
for (int c : qs[v]) {
Modify(rt[v], rt[v], 1, inf, c, +1);
cs[v] += 1;
}
for (int u : g[v]) {
if (u == pv) {
continue;
}
rt[u] = rt[v];
cs[u] = cs[v];
Dfs(u, v);
}
}
int LCA(int x, int y) {
if (dep[x] > dep[y]) {
swap(x, y);
}
for (int j = L - 1; j >= 0; j--) {
if (dep[pr[y][j]] >= dep[x]) {
y = pr[y][j];
}
}
for (int j = L - 1; j >= 0; j--) {
if (pr[x][j] != pr[y][j]) {
x = pr[x][j];
y = pr[y][j];
}
}
return (x == y ? x : pr[x][0]);
}
long long Get(int s, int t, int w, int f) {
int p = FindFirst(rt[s], rt[t], rt[w], 1, inf, f);
int cc = GetCnt(rt[s], 1, inf, 1, p - 1) + GetCnt(rt[t], 1, inf, 1, p - 1)
- 2 * GetCnt(rt[w], 1, inf, 1, p - 1);
long long res = GetSum(rt[s], 1, inf, 1, p - 1) + GetSum(rt[t], 1, inf, 1, p - 1)
- 2 * GetSum(rt[w], 1, inf, 1, p - 1);
res += p * 1LL * (f - cc);
return res;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n, m, q;
cin >> n >> m >> q;
for (int i = 1; i < n; i++) {
cin >> x[i] >> y[i];
--x[i]; --y[i];
g[x[i]].push_back(y[i]);
g[y[i]].push_back(x[i]);
}
Go(0, 0);
for (int i = 1; i < n; i++) {
if (dep[x[i]] > dep[y[i]]) {
swap(x[i], y[i]);
}
}
for (int i = 0; i < m; i++) {
int p, c;
cin >> p >> c;
qs[y[p]].push_back(c);
}
Dfs(0, 0);
while (q--) {
int s, t, a;
long long b;
cin >> s >> t >> a >> b;
--s; --t;
int w = LCA(s, t);
int f = cs[s] + cs[t] - 2 * cs[w];
int low = 0, high = a, ans = -1;
while (low <= high) {
int mid = low + high >> 1;
if (Get(s, t, w, max(0, f - (a - mid))) <= b) {
ans = mid;
low = mid + 1;
} else {
high = mid - 1;
}
}
cout << ans << '\n';
}
return 0;
}
