#include <bits/stdc++.h>
using namespace std;
const int sz=2000;
int n,m,q,u,v,st[100005],ed[100005],road[100005],vis[100005],ptl,ptr;
int tin,in[100005],out[100005],lift[25][100005],id[100005];
long long gold[100005],sil[100005],freq[100005],sum[2005],bkfq[2005],ans[100005];
vector<pair<int,int> > grh[100005];
pair<int,pair<int,int> > qry[100005];
vector<int> ckpt[100005];
pair<long long,int> pc[100005];
int blck(int x){
return x/sz+(x%sz>0);
}
bool is(int x,int y){
return in[x]<=in[y] && out[x]>=out[y];
}
int lca(int x,int y){
if (is(x,y)) return x;
if (is(y,x)) return y;
for (int i=20;i>=0;i--){
if (lift[i][x] && !is(lift[i][x],y)) x=lift[i][x];
}
return lift[0][x];
}
void dfs(int x,int p){
in[x]=++tin; lift[0][x]=p;
for (int i=1;i<=20;i++) lift[i][x]=lift[i-1][lift[i-1][x]];
for (pair<int,int> i:grh[x]){
if (i.first==p) continue;
road[i.first]=i.second;
dfs(i.first,x);
}
out[x]=++tin;
id[out[x]]=id[in[x]]=x;
}
bool cmp(pair<int,pair<int,int> > x,pair<int,pair<int,int> > y){
if (x.second.first/sz!=y.second.first/sz) return x.second.first<y.second.first;
else return x.second.second<y.second.second;
}
void upd(int x){
x=id[x];
// if (vis[x]) cout<<"del :";
// else cout<<"add :";
// cout<<x<<"\n";
if (vis[x]){
vis[x]=0;
if (road[x]) {
for (int i:ckpt[road[x]]){
freq[i]--; bkfq[blck(i)]--;
sum[blck(i)]-=pc[i].first;
}
}
}
else {
vis[x]=1;
if (road[x]){
for (int i:ckpt[road[x]]){
freq[i]++; bkfq[blck(i)]++;
sum[blck(i)]+=pc[i].first;
}
}
}
}
long long output(long long x){
return (x<0LL?-1LL:x);
}
int main(){
scanf("%d%d%d",&n,&m,&q);
for (int i=1;i<n;i++){
scanf("%d%d",&u,&v);
grh[u].emplace_back(make_pair(v,i));
grh[v].emplace_back(make_pair(u,i));
}
dfs(1,0);
for (int i=1;i<=m;i++) scanf("%d%lld",&pc[i].second,&pc[i].first);
for (int i=1;i<=q;i++){
scanf("%d%d%lld%lld",st+i,ed+i,gold+i,sil+i);
int anc=lca(st[i],ed[i]);
if (in[st[i]]>in[ed[i]]) swap(st[i],ed[i]);
if (anc==st[i]) qry[i].second=make_pair(in[st[i]],in[ed[i]]);
else qry[i].second=make_pair(out[st[i]],in[ed[i]]);
qry[i].first=i;
}
sort(qry+1,qry+1+q,cmp);
sort(pc+1,pc+1+m);
for (int i=1;i<=m;i++) ckpt[pc[i].second].push_back(i);
ptl=1; ptr=0;
for (int i=1;i<=q;i++){
int l=st[qry[i].first]; int r=ed[qry[i].first];
//cout<<l<<" "<<r<<"\n"<<qry[i].second.first<<" "<<qry[i].second.second<<"\n";
while (ptr<qry[i].second.second) upd(++ptr);
while (ptr>qry[i].second.second) upd(ptr--);
while (ptl<qry[i].second.first) upd(ptl++);
while (ptl>qry[i].second.first) upd(--ptl);
int anc=lca(l,r);
bool can=true;
if (anc==l) upd(in[l]);
for (int j=1;j<=blck(m);j++){
if (!can) ans[qry[i].first]+=bkfq[j];
else if (sum[j]<=sil[qry[i].first]) sil[qry[i].first]-=sum[j];
else {
can=false;
for (int k=sz*(j-1)+1;k<=min(m,sz*j);k++){
long long d=min(sil[qry[i].first]/pc[k].first,freq[k]);
sil[qry[i].first]-=d*pc[k].first;
ans[qry[i].first]+=freq[k]-d;
}
}
}
if (anc==l) upd(in[l]);
}
for (int i=1;i<=q;i++) printf("%lld\n",output(gold[i]-ans[i]));
}
