#include <bits/stdc++.h>
using namespace std;
//#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<long long,int>pii;
typedef pair<pii,pii>pi2;
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
inline pii combine(pii a, pii b){
return {a.first+b.first,a.second+b.second};
}
struct node{
int s,e,m;
pii v;
node *l,*r;
node(int ss, int ee):s(ss),e(ee),m((s+e)>>1),v({0,0}){
if(s!=e){
l=new node(s,m);
r=new node(m+1,e);
}
}
node(node *u){
s=u->s,e=u->e,m=u->m,v=u->v,l=u->l,r=u->r;
}
void upd(int x, pii y){
if(s==e){
v.first+=y.first;
v.second+=y.second;
return;
}
if(x<=m){
l=new node(l);
l->upd(x,y);
}
else{
r=new node(r);
r->upd(x,y);
}
v=combine(l->v,r->v);
}
pii query(int x, int y){
if(x<=s&&y>=e){
return v;
}
if(y<=m) return l->query(x,y);
if(x>m) return r->query(x,y);
return combine(l->query(x,m),r->query(m+1,y));
}
}*root[100005];
vector<int>adj[100005];
int in[100005];
int out[100005];
int d[100005];
int two[25][100005];
int ptr=0;
void dfs(int index, int par){
in[index]=++ptr;
for(int x=0;x<20;x++){
two[x+1][index]=two[x][two[x][index]];
}
for(auto it:adj[index]){
if(it==par) continue;
two[0][it]=index;
d[it]=d[index]+1;
dfs(it,index);
}
out[index]=++ptr;
}
int lca(int a, int b){
if(d[a]>d[b]) swap(a,b);
int diff=d[b]-d[a];
for(int x=0;x<19;x++){
if(diff&(1<<x)){
b=two[x][b];
}
}
if(a==b) return a;
for(int x=19;x>=0;x--){
if(two[x][a]!=two[x][b]){
a=two[x][a];
b=two[x][b];
}
}
return two[0][a];
}
void solve(){
int n,m,q;
cin >> n >> m >> q;
int temp,temp2;
pii edge[n-1];
for(int x=0;x<n-1;x++){
cin >> temp >> temp2;
adj[temp].push_back(temp2);
adj[temp2].push_back(temp);
edge[x]={temp,temp2};
}
dfs(1,-1);
pii check[m]; //cost edge
for(int x=0;x<m;x++){
cin >> check[x].second >> check[x].first;
}
sort(check,check+m);
root[0]=new node(0,200005);
for(int x=0;x<m;x++){
root[x+1]=new node(root[x]);
int road=check[x].second-1;
int index;
if(d[edge[road].first] > d[edge[road].second]){
index=edge[road].first;
}
else index=edge[road].second;
//show(index,index);
root[x+1]->upd(in[index],{check[x].first,1});
root[x+1]->upd(out[index],{-check[x].first,-1});
//for(int y=0;y<2*n;y++){
//cout << root[x+1]->query(y,y).second << " ";
//}
//cout << endl;
}
int from,to;
long long a,b; //gold silver
for(int x=0;x<q;x++){
cin >> from >> to >> a >> b;
int hold=lca(from,to);
int l=0;
int r=m;
pii best={0,0};
int mid;
while(l<=r){
mid=(l+r)/2;
pii que=root[mid]->query(0,in[from]);
pii que2=root[mid]->query(0,in[to]);
pii que3=root[mid]->query(0,in[hold]);
//show(mid,mid);
//show3(que.first,que.first,que2.first,que2.first,que3.first,que3.first);
//show(total,que.first+que2.first-que3.first*2,b,b)
if(que.first+que2.first-que3.first*2<=b){
best={mid,que.second+que2.second-que3.second*2};
l=mid+1;
}
else r=mid-1;
}
//show3(a,root[m]->query(0,in[from]),b,root[m]->query(0,in[to]),c,root[m]->query(0,in[hold]));
long long len=root[m]->query(0,in[from]).second+root[m]->query(0,in[to]).second-2*root[m]->query(0,in[hold]).second - best.second;
//show(best.second,best.second);
//show(len,len);
if(a-len<0){
cout << -1 << "\n";
}
else cout << a-len << "\n";
}
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
//freopen("in.txt","w",stdout);
//cin >> t;
while(t--){
solve();
}
}
