#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
//#include<bits/extc++.h>
//__gnu_pbds
int n,m,q;
struct Query{
int a,b;
int x,y;
int ans;
};
struct request{
int node;
ll v;
};
const int N = 1e5+5;
vector<int> side[N];
vector<request> Req;
vector<Query> Que;
// tree stuff
pair<int,int> dep[N];
int father[N][20];
int t;
void dfs(int cur){
dep[cur].first=++t;
for(auto i : side[cur]){
if(!dep[i].first){
father[i][0] = cur;
dfs(i);
}
}
dep[cur].second=++t;
}
bool is_father_of(int a,int b){
return (dep[b].first>=dep[a].first && dep[b].second<=dep[a].second);
}
int lca(int a,int b){
if(is_father_of(a,b)) return a;
if(is_father_of(b,a)) return b;
for(int j=19;j>=0;j--){
if(!is_father_of(father[b][j],a)) b = father[b][j];
}
return father[b][0];
}
//------------------------
//bit stuff
vector<ll> vsum;
vector<ll> cnt;
void add(ll v,int ind,vector<ll> &bit){
while(ind<=2*n){
bit[ind]+=v;
ind+=(ind&-ind);
}
}
ll query(int ind,vector<ll> &bit){
ll result = 0;
while(ind){
result+=bit[ind];
ind-=(ind&-ind);
}
return result;
}
//--------------------
// total binary search stuff
void do_thing(int l,int r,int mi){
for(int i=l;i<r;i++){
if(i<0) continue;
add(mi*Req[i].v,dep[Req[i].node].first,vsum);
add(-1*mi*Req[i].v,dep[Req[i].node].second,vsum);
add(mi,dep[Req[i].node].first,cnt);
add(-1*mi,dep[Req[i].node].second,cnt);
}
}
void split(vector<int> &qry,vector<int> &lft,vector<int> &rgt,int k){
for(auto i : qry){
long long sum = 0;
sum+=query(dep[Que[i].a].first,vsum);
sum+=query(dep[Que[i].b].first,vsum);
sum-=2*query(dep[lca(Que[i].a,Que[i].b)].first,vsum);
// cout<<i<<" "<<sum<<" "<<Que[i].y<<" "<<k<<" -split"<<(sum>Que[i].y)<<"\n";
if(sum>Que[i].y) lft.push_back(i);
else rgt.push_back(i);
}
vector<int>().swap(qry);
}
void total_BS(int l,int r,vector<int> &qry){
if(r-l<=1){
for(auto i : qry) Que[i].ans=l;
return;
}
int mid = (l+r)/2;
do_thing(l,mid,1);
vector<int> lft,rgt;
split(qry,lft,rgt,mid);
total_BS(mid,r,rgt);
do_thing(l,mid,-1);
total_BS(l,mid,lft);
}
//-----------------------------------
signed main(){
ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
cin>>n>>m>>q;
Que.resize(q);
vsum.resize(2*n+1,0);
cnt.resize(2*n+1,0);
vector<pair<int,int> > es;
for(int i=0;i<n-1;i++){
int a,b;cin>>a>>b;
es.push_back({a,b});
side[a].push_back(b);
side[b].push_back(a);
}
for(int i=0;i<20;i++){
father[1][i]=1;
}
dfs(1);
for(int j=1;j<20;j++){
for(int i=2;i<=n;i++){
father[i][j] = father[father[i][j-1]][j-1];
}
}
for(int i=0;i<m;i++){
int p;cin>>p;
p--;
int c;cin>>c;
if(dep[es[p].first]<dep[es[p].second]) swap(es[p].first,es[p].second);
Req.push_back({es[p].first,c});
}
sort(Req.begin(),Req.end(),[](const request &a,const request &b){return a.v<b.v;});
/*
cout<<endl;
for(auto i : Req){
cout<<i.node<<" "<<i.v<<endl;
}
cout<<endl;
*/
vector<int> tmp;
for(int i=0;i<q;i++){
cin>>Que[i].a>>Que[i].b>>Que[i].x>>Que[i].y;
tmp.push_back(i);
}
total_BS(0,m+1,tmp);
int ttt = 0;
vector<int> anssort;
for(int i=0;i<q;i++){
anssort.push_back(i);
}
/*cout<<"\n";
for(int i=0;i<q;i++){
cout<<Que[i].ans<<"\n";
}
cout<<"\n\n\n-----\n";
*/
sort(anssort.begin(),anssort.end(),[&](const int a,const int b){return Que[a].ans<Que[b].ans;});
vector<ll> realans(q,0);
for(int i=0;i<q;i++){
do_thing(ttt,Que[anssort[i]].ans,1);
ttt = Que[anssort[i]].ans;
realans[anssort[i]]+=Que[anssort[i]].x;
realans[anssort[i]]+=query(dep[Que[anssort[i]].a].first,cnt);
realans[anssort[i]]+=query(dep[Que[anssort[i]].b].first,cnt);
realans[anssort[i]]-=2*query(dep[lca(Que[anssort[i]].a,Que[anssort[i]].b)].first,cnt);
}
// cout<<ttt<<endl;
do_thing(ttt,m,1);
for(int i=0;i<q;i++){
realans[i]-=query(dep[Que[i].a].first,cnt);
realans[i]-=query(dep[Que[i].b].first,cnt);
realans[i]+=2*query(dep[lca(Que[i].a,Que[i].b)].first,cnt);
}
for(int i=0;i<q;i++){
cout<<max(-1LL,realans[i])<<"\n";
}
return 0;
}
