#include<bits/stdc++.h>
using namespace std;
using ll = long long;
struct citizen {
int s, t;
ll x, y;
int inx;
};
struct edge {
int to, i;
};
int n, m, q;
vector<pair<int, int>> edges;
vector<pair<int, int>> checkpoints;
vector<citizen> citizens;
vector<int> answers;
namespace Subtask1 {
const int N = 1e5 + 10;
vector<edge> g[N];
int depth[N], pre[N], T;
int inx[N] = {};
ll C;
void precalc(int s, int p) {
pre[s] = p;
for(auto [to, i] : g[s]) {
if(to == p) continue;
depth[to] = depth[s] + 1;
inx[to] = i;
precalc(to, s);
}
}
void init() {
int koll = 0;
for(auto [u, v] : edges) {
g[u].push_back({v, koll});
g[v].push_back({u, koll});
koll++;
}
precalc(1, 1);
for(citizen cit : citizens) {
set<int> ee;
int u = cit.s, v = cit.t;
while(u != v) {
if(depth[u] >= depth[v]) {
ee.insert(inx[u]);
u = pre[u];
} else {
ee.insert(inx[v]);
v = pre[v];
}
}
set<ll> st;
ll sum = 0, k = 0;
for(auto [p, c] : checkpoints) {
if(!ee.count(p)) continue;
st.insert(c);
sum += c;
if(sum > cit.y) {
k++;
sum -= *(--st.end());
st.erase(--st.end());
}
}
answers[cit.inx] = (cit.x < k ? -1 : cit.x - k);
}
}
};
namespace Subtask2 {
const int N = 1e5 + 10;
vector<int> g[N];
int tin[N], tout[N], anc[N][17], T;
int f[N] = {};
int cnt[N] = {};
ll C;
void precalc(int s, int p) {
tin[s] = T++;
anc[s][0] = p;
cnt[s] = cnt[p] + f[s];
for(int i = 1; i < 17; i++)
anc[s][i] = anc[anc[s][i - 1]][i - 1];
for(int to : g[s]) {
if(to == p) continue;
precalc(to, s);
}
tout[s] = T++;
}
bool up(int u, int v) {
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
int lca(int u, int v) {
if(up(u, v)) return u;
if(up(v, u)) return v;
for(int i = 16; i >= 0; i--) {
if(!up(anc[u][i], v)) u = anc[u][i];
}
return anc[u][0];
}
void init() {
for(auto [u, v] : edges) {
g[u].push_back(v);
g[v].push_back(u);
}
precalc(1, 1);
for(auto [p, c] : checkpoints) {
auto [u, v] = edges[p];
if(tin[u] > tin[v]) swap(u, v);
f[v]++;
C = c;
}
precalc(1, 1);
for(citizen c : citizens) {
int u = lca(c.s, c.t);
int k = cnt[c.s] + cnt[c.t] - 2 * cnt[u];
if(C == 0) answers[c.inx] = c.x;
else {
int ans = c.x - max(k - c.y / C, 0ll);
if(ans < 0) ans = -1;
answers[c.inx] = ans;
}
// cout << c.inx << ' ' << ans << '\n';
}
}
};
int main() {
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin >> n >> m >> q;
for(int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
edges.push_back({u, v});
}
for(int i = 0; i < m; i++) {
int p, c;
cin >> p >> c;
p--;
checkpoints.push_back({p, c});
}
for(int i = 0; i < q; i++) {
citizen s;
cin >> s.s >> s.t >> s.x >> s.y;
s.inx = i;
citizens.push_back(s);
}
answers.resize(q);
if(n <= 2000) {
Subtask1::init();
} else {
Subtask2::init();
}
for(int c : answers)
cout << c << '\n';
}
