#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define ld long double
#define ff first
#define ss second
#define ln "\n"
#define mp make_pair
#define pb push_back
#define INF (ll)2e18
#define MOD 998244353
struct SegTree{
vector<vector<ll>> t;
vector<vector<ll>> tpref;
ll sz, rsz;
void init(ll N){
sz=N*4; rsz=N;
tpref.resize(sz); t.resize(sz);
}
void build(ll tl, ll tr, ll v, vector<vector<ll>> &a){
if (tl==tr){
t[v] = a[tl];
tpref[v]=a[tl];
for (ll i=1; i<(ll)tpref[v].size(); i++) tpref[v][i]+=tpref[v][i-1];
}else{
ll tm = (tl+tr)/2;
build(tl, tm, v*2, a);
build(tm+1, tr, v*2+1, a);
merge(t[v*2].begin(), t[v*2].end(), t[v*2+1].begin(), t[v*2+1].end(), back_inserter(t[v]));
tpref[v].resize(t[v].size());
for (ll i=0; i<(ll)t[v].size(); i++){
tpref[v][i]=(i?tpref[v][i-1]:0ll)+t[v][i];
}
}
}
pair<ll, ll> query(ll tl, ll tr, ll v, ll l, ll r, ll x){
if (tl==l and tr==r){
ll ind = upper_bound(t[v].begin(), t[v].end(), x)-t[v].begin()-1;
pair<ll, ll> ret = {0, 0};
if (ind>=0){
ret=mp(ind+1ll, tpref[v][ind]);
}
return ret;
}else if (l>r) return {0, 0};
else{
ll tm = (tl+tr)/2;
pair<ll, ll> resl = query(tl, tm, v*2, l, min(r, tm), x);
pair<ll, ll> resr = query(tm+1, tr, v*2+1, max(l, tm+1), r, x);
return {resl.ff+resr.ff, resl.ss+resr.ss};
}
}
void build(vector<vector<ll>> &a){
build(0, rsz-1, 1, a);
}
pair<ll, ll> query(ll l, ll r, ll x){
// cout << l << " - " << r << " - " << x << " -> ";
if (l>r) swap(l, r);
pair<ll, ll> ret=query(0, rsz-1, 1, l, r, x);
// cout << ret.ff << " " << ret.ss << ln;
return ret;
}
};
struct edge{
ll u, v; vector<ll> control;
};
struct HLD{
ll n; vector<edge> e;
vector<vector<ll>> A;
vector<ll> sz, level;
vector<ll> eid, nxt;
vector<vector<ll>> euler, bin /*just in case*/;
SegTree ds;
void dfs1(ll u, ll p, ll clev){
bin[u][0]=p; level[u]=clev; sz[u]=1; ll mxsz=0;
for (ll i=1; i<20; i++) bin[u][i]=bin[bin[u][i-1]][i-1];
for (auto &i:A[u]){
ll v = e[i].u^e[i].v^u;
if (v==p) continue;
dfs1(v, u, clev+1); sz[u]+=sz[v];
if (mxsz<sz[v]) swap(i, A[u][0]), mxsz=sz[v];
}
}
void dfs2(ll u, ll p){
bool first=1;
for (auto i:A[u]){
ll v = e[i].u^e[i].v^u;
if (v==p) continue;
eid[v]=euler.size();
euler.push_back(e[i].control);
if (first) nxt[v]=nxt[u];
else nxt[v]=v;
dfs2(v, u); first=0;
}
}
HLD(ll N, vector<edge> &_e){
n=N; e=_e; A.resize(n+1);
sz.resize(n+1); level.resize(n+1);
nxt.resize(n+1); bin.resize(n+1, vector<ll>(20));
eid.resize(n+1);
for (ll i=0; i<n-1; i++){
A[e[i].u].push_back(i); A[e[i].v].push_back(i);
}
nxt[1]=1; euler.push_back(vector<ll>());
dfs1(1, 1, 1); dfs2(1, 1); ds.init(N);
ds.build(euler);
// for (ll i=1; i<=n; i++) cout << level[i] << " ";
// cout<<endl;
}
pair<ll, ll> queryLOW(ll u, ll v, ll c){
// cout << "ENT" << u << " - " << v << " - " << c << endl;
if (u==v) return {0, 0};
pair<ll, ll> res = {0, 0};
while (nxt[u]!=nxt[v]){
// cout << u << " - " << v << " <-> ";
if (level[nxt[u]]<level[nxt[v]]) swap(u, v);
pair<ll, ll> ret=ds.query(eid[u], eid[nxt[u]], c);
res.ff+=ret.ff; res.ss+=ret.ss;
u=bin[nxt[u]][0];
}
// cout << u << " - " << v << endl;
// cout << "CAME" << endl;
if (u!=v){
if (level[u]<level[v]) swap(u, v);
ll jump = level[u]-level[v]-1;
ll tu = u;
for (ll i=0; i<20; i++){
if (jump&(1ull<<i)){
tu=bin[tu][i];
}
}
pair<ll, ll> ret=ds.query(eid[u], eid[tu], c);
res.ff+=ret.ff; res.ss+=ret.ss;
}
// cout << "DONE -> " << res.ff << " - " << res.ss << endl;
return res;
}
ll query(ll u, ll v, ll s, ll g){
ll l=0, r=s+2;
while (l+1<r){
ll mid = (l+r)/2;
if (queryLOW(u, v, mid).ss<=s) l=mid;
else r=mid;
}
pair<ll, ll> data = queryLOW(u, v, l);
ll total = queryLOW(u, v, 2e9).ff;
total-=data.ff; s-=data.ss; total-=s/(l+1);
return max(-1ll, g-total);
}
};
void solve(){
ll n, m, q; cin >> n >> m >> q;
vector<edge> e(n-1);
for (ll i=0; i<n-1; i++){
cin >> e[i].u >> e[i].v;
}
for (ll i=0; i<m; i++){
ll id, x; cin >> id >> x;
e[id-1].control.push_back(x);
}
for (ll i=0; i<n-1; i++){
sort(e[i].control.begin(), e[i].control.end());
}
HLD tr(n, e);
// return;
while (q--){
ll u, v, g, s; cin >> u >> v >> g >> s;
cout << tr.query(u, v, s, g) << ln;
}
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(nullptr);
#ifdef LOCAL
auto start = chrono::high_resolution_clock::now();
#endif
ll t=1;
// cin >> t;
while (t--) solve();
#ifdef LOCAL
auto duration = chrono::duration_cast<chrono::microseconds>(chrono::high_resolution_clock::now() - start);
cout << setprecision(0) << fixed << "time: " << (double)duration.count()/1000.0 << " milliseconds" << endl;
#endif
}
