// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define int long long
#define endl "\n"
#define fi first
#define se second
const int M=1e9+7;
const int inf = 1e9;
const int LOG=17;
const int N=1e5+5;
int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r;
vector<int>a[N];
int p[N];
int st[LOG][N];
int pm[N];
int di[N];
void makest(){
for (int i=1;i<N;i++){
st[0][i]=p[i];
}
for (int j=1;j<LOG;j++){
for (int i=1;i<N;i++){
st[j][i]=st[j-1][st[j-1][i]];
}
}
}
int up(int x,int d){
int k=LOG-1;
while (k>=0){
if ((1<<k)<=d){
d-=1<<k;
x=st[k][x];
}
k--;
}
return x;
}
int lca(int x,int y){
if (di[x]<di[y]){
swap(x,y);
}
x=up(x,di[x]-di[y]);
if (x==y)return x;
int k=LOG-1;
while (k>=0){
if (st[k][x]!=st[k][y]){
x=st[k][x];
y=st[k][y];
}
k--;
}
return p[x];
}
void solve()
{
cin >> n >> m >> q;
map<pair<int,int>,int>d;
for (int i=1;i<n;i++){
cin >> x >> y;
a[x].push_back(y);
a[y].push_back(x);
d[{x,y}]=i;
d[{y,x}]=i;
}
vector<vector<int>>ch(n);
for (int i=0;i<m;i++){
cin >> x >> y;
c=y;
ch[x].push_back(y);
pm[x]++;
}
p[1]=0;
queue<int>o;
vector<int>vi(n+1);
o.push(1);
vi[1]=1;
while(o.size()){
int h=o.front();
o.pop();
for (int i:a[h]){
if (vi[i])continue;
vi[i]=1;
di[i]=di[h]+1;
o.push(i);
pm[i]+=pm[h];
p[i]=h;
}
}
if (n<=2000 and m<=2000 and q<=2000){
for (int i=0;i<q;i++){
int g,s;
cin >> x >> y >> g >> s;
vector<int>l;
while (x!=y){
if (di[x]<di[y]){
swap(x,y);
}
for (int k:ch[d[{x,p[x]}]]){
l.push_back(k);
}
x=p[x];
}
sort(l.begin(),l.end());
for (int j:l){
if (j<=s){
s-=j;
}
else{
g--;
}
}
cout << max(-1ll,g) << endl;
}
return;
}
makest();
for (int i=0;i<q;i++){
int g,s;
cin >> x >> y >> g >> s;
g+=s/c;
z=lca(x,y);
cout << max(-1ll,g-(pm[x]+pm[y]-2*pm[z])) << endl;
}
}
signed main()
{
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE
cout << fixed << setprecision(9);
srand(time(0));
// int t=1;
// cin >> t;
for (int _=1;_<=t;_++){
solve();
q++;
}
}
