#include<bits/stdc++.h>
using namespace std;
#define pb push_back
int N, M, Q;
vector<vector<int>> adj;
vector<int> par, sz, anc, flat, pos;
vector<pair<int, int>> e, ch;
vector<int> S, T, X;
vector<long long> Y;
void dfs_sz(int s) {
sz[s] = 1;
if(adj[s][0] == par[s] && (int)adj[s].size() >= 2) swap(adj[s][0], adj[s][1]);
for(auto& u : adj[s]) {
if(u == par[s]) continue;
par[u] = s;
dfs_sz(u);
sz[s] += sz[u];
if(sz[adj[s][0]] < sz[u]) swap(adj[s][0], u);
}
}
void build_hld(int s, int r) {
pos[s] = (int)flat.size();
flat.pb(s);
anc[s] = r;
for(auto& u : adj[s]) {
if(u == par[s]) continue;
build_hld(u, (u == adj[s][0] ? r : u));
}
}
int LCA(int a, int b) {
if(pos[a] > pos[b]) swap(a, b);
if(anc[a] == anc[b]) return a;
return LCA(a, par[anc[b]]);
}
vector<long long> bit;
void update(int ind, long long val) {
++ind;
while(ind <= N) {
bit[ind] += val;
ind += ind & -ind;
}
}
long long pref_sum(int ind) {
++ind;
long long sum = 0;
while(ind > 0) {
sum += bit[ind];
ind -= ind & -ind;
}
return sum;
}
long long Query(int l, int r) {
return pref_sum(r) - pref_sum(l - 1);
}
long long hld_path(int u, int v) {
if(anc[u] == anc[v]) return Query(pos[v], pos[u]);
return Query(pos[anc[u]], pos[u]) + hld_path(par[anc[u]], v);
}
int32_t main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> N >> M >> Q;
adj.resize(N);
e.resize(N - 1);
for(int i = 0; i + 1 < N; ++i) {
int u, v; cin >> u >> v; --u; --v;
e[i] = {u, v};
adj[u].pb(v);
adj[v].pb(u);
}
{ // hld
par.resize(N);
sz.resize(N);
par[0] = -1;
dfs_sz(0);
anc.resize(N);
pos.resize(N);
build_hld(0, -1);
}
for(int i = 0; i + 1 < N; ++i) {
if(par[e[i].second] == e[i].first) swap(e[i].first, e[i].second);
}
for(int i = 0; i < M; ++i) {
int x, y; cin >> x >> y;
ch.pb({y, e[x - 1].first});
}
sort(begin(ch), end(ch));
S.resize(Q);
T.resize(Q);
X.resize(Q);
Y.resize(Q);
for(int i = 0; i < Q; ++i) {
cin >> S[i] >> T[i] >> X[i] >> Y[i];
--S[i]; --T[i];
}
vector<int> TL(Q, 0), TR(Q, M);
while(true) {
bool any = false;
vector<vector<int>> Pos(M + 1);
for(int i = 0; i < Q; ++i) {
if(TL[i] == TR[i]) continue;
any = true;
int TM = (TL[i] + TR[i] + 1) / 2;
Pos[TM].pb(i);
}
if(!any) break;
bit = vector<long long>(N + 1, 0LL);
for(int i = 0; i < M; ++i) {
update(pos[ch[i].second], ch[i].first);
for(auto& u : Pos[i + 1]) {
int L = LCA(S[u], T[u]);
long long sum = hld_path(S[u], L) + hld_path(T[u], L) - 2 * hld_path(L, L);
if(sum <= Y[u]) {
TL[u] = i + 1;
} else {
TR[u] = i;
}
}
}
}
vector<int> ans(Q);
bit = vector<long long>(N + 1, 0LL);
vector<vector<int>> Pos(M + 1);
for(int i = 0; i < Q; ++i) {
Pos[TL[i]].pb(i);
}
for(int i = M; i >= 0; --i) {
if(i < M) update(pos[ch[i].second], 1);
for(int& u : Pos[i]) {
if(i == M) {
ans[u] = X[u];
continue;
}
int L = LCA(S[u], T[u]);
long long sum = hld_path(S[u], L) + hld_path(T[u], L) - 2 * hld_path(L, L);
ans[u] = max(-1LL, X[u] - sum);
}
}
for(auto& u : ans) {
cout << u << '\n';
}
return 0;
}
