#include <bits/stdc++.h>
//#pragma GCC optimize("O3")
//#pragma GCC target("avx,avx2,fma")
#define sz(x) (x).size()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
using namespace std;
using ll = long long;
using db = long double; // or double, if TL is tight
using str = string;
using ii = pair<int, int>;
using pl = pair<ll, ll>;
using vi = vector<int>;
using vll = vector<ll>;
template<class T>
struct AIB {
int n;
vector<T> V;
AIB(int N) : n(N + 1), V(N + 1) {}
void update(int p, T v) {
++p;
while(p < n) {
V[p] += v;
p += p & -p;
}
}
T query(int p) {
++p;
T re = 0;
while(p) {
re += V[p];
p -= p & -p;
}
return re;
}
};
struct tree {
int n;
vi par, niv, in, out;
vector<vector<pair<int, ll> > > L;
vector<vi> Anc;
AIB<int> NR;
AIB<ll> COST;
tree(int N) : n(N), L(N), par(N), niv(N), in(N),
out(N), NR(2 * N), COST(2 * N) {}
void add_edge(int u, int v, ll w) {
L[u].push_back({v, w});
L[v].push_back({u, w});
}
void init() {
function<void(int, int, int)> dfs = [&](int u, int p, int li) {
static int tmr = 0;
niv[u] = li;
in[u] = tmr++;
par[u] = p;
for(auto [it, w] : L[u]) {
if(it != p) {
dfs(it, u, li + 1);
}
}
out[u] = tmr++;
};
dfs(0, -1, 0);
Anc.push_back(par);
for(int k = 1; (1 << k) <= n; ++k) {
Anc.push_back(vi(n, -1));
for(int i = 0; i < n; ++i) {
Anc[k][i] = Anc[k-1][i] == -1 ? -1 : Anc[k-1][Anc[k-1][i]];
}
}
}
int lift(int u, int nr) {
for(int i = 0; i < (int)sz(Anc); ++i) {
if(nr & (1 << i))
u = Anc[i][u];
}
return u;
}
int lca(int u, int v) {
if(niv[u] > niv[v]) swap(u, v);
v = lift(v, niv[v] - niv[u]);
if(u == v) return u;
for(int i = int(sz(Anc)) - 1; i >= 0; --i) {
if(Anc[i][u] != Anc[i][v]) {
u = Anc[i][u];
v = Anc[i][v];
}
}
return par[u];
}
int dist(int u, int v) { return niv[u] + niv[v] - 2 * niv[lca(u, v)]; }
void enable(int u, int v, ll w) {
if(niv[u] > niv[v]) swap(u, v);
NR.update(in[v], 1);
NR.update(out[v], -1);
COST.update(in[v], w);
COST.update(out[v], -w);
}
void disable(int u, int v, ll w) {
if(niv[u] > niv[v]) swap(u, v);
NR.update(in[v], -1);
NR.update(out[v], 1);
COST.update(in[v], -w);
COST.update(out[v], w);
}
pair<ll, int> query(int u, int v) {
int l = lca(u, v);
int nr = NR.query(in[u]) + NR.query(in[v]) - 2 * NR.query(in[l]);
ll re = COST.query(in[u]) + COST.query(in[v]) - 2 * COST.query(in[l]);
return {re, nr};
}
};
int main() {
cin.tie(0);
ios_base::sync_with_stdio(0);
int n, m, q;
cin >> n >> m >> q;
vector<tuple<int, int, ll> > E;
for(int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
--u; --v;
E.push_back({u, v, 0});
}
vector<pair<int, ll> > P;
for(int i = 0; i < m; ++i) {
int p, c;
cin >> p >> c;
P.emplace_back(p, c);
}
tree Tr(n);
for(auto [u, v, w] : E) {
Tr.add_edge(u, v, w);
}
Tr.init();
vi S(q), T(q), X(q), Y(q), St(q), Dr(q), Mij(q), UltNr(q), Total(q);
for(int i = 0; i < q; ++i) {
cin >> S[i] >> T[i] >> X[i] >> Y[i];
--S[i]; --T[i];
St[i] = 0;
Dr[i] = m;
}
sort(all(P), [&](auto a, auto b) { return a.second < b.second; });
int schimbat = 1;
while(schimbat) {
schimbat = 0;
vector<vi> Q(n);///query-uri de dinainte de a aduaga a i - 1 -a muchie
for(int i = 0; i < q; ++i) {
if(St[i] != Dr[i]) {
schimbat = 1;
}
Mij[i] = (St[i] + Dr[i] + 1) / 2;
Q[Mij[i]].push_back(i);
}
for(int i = 0; i <= m; ++i) {
if(i) {
auto [p, w] = P[i - 1];
auto [u, v, ceva] = E[p - 1];
Tr.enable(u, v, w);
}
for(auto it : Q[i]) {
auto [cost, nr] = Tr.query(S[it], T[it]);
if(cost <= Y[it]) {
St[it] = Mij[it];
UltNr[it] = nr;
} else {
Dr[it] = Mij[it] - 1;
}
}
}
for(int i = 0; i < q; ++i) {
Total[i] = Tr.query(S[i], T[i]).second;
}
for(int i = 0; i <= m; ++i) {
if(i) {
auto [p, w] = P[i - 1];
auto [u, v, ceva] = E[p - 1];
Tr.disable(u, v, w);
}
}
}
for(int i = 0; i < q; ++i) {
int ramase = X[i] - Total[i] + UltNr[i];
//printf("Pt query %d dist=%d UltNr=%d\n", i, Tr.dist(S[i], T[i]), UltNr[i]);
cout << max(ramase, -1) << "\n";
}
return 0;
}
