//####################
//TwoCurrencies
//####################
#include<bits/stdc++.h>
#define int long long
using namespace std;
const int maxiN = 1000000;
const int LOG = 17;
vector<int> links[maxiN];
int depth[maxiN];
int up[maxiN][LOG];
void root(int node,int d=0,int parent=-1){
up[node][0]=parent;
depth[node]=d;
for(int v:links[node])if(v!=parent){
root(v,d+1,node);
}
}
int getK(int node,int K){
for(int i=LOG-1;i>=0;i--){
if((K>>i)&1){
node = up[node][i];
}
}
return node;
}
int LCA(int a,int b){
if(depth[b]>depth[a])swap(a,b);
a = getK(a,depth[a]-depth[b]);
if(a==b){
return a;
}
for(int l = LOG-1;l>=0;l--){
if(up[a][l]!=up[b][l]){
a = up[a][l];
b = up[b][l];
}
}
return up[a][0];
}
map<int,vector<int>> peages;
vector<int> val[maxiN];
signed main(){
fill(depth,depth+maxiN,-1);
int n,m,q;cin>>n>>m>>q;
vector<pair<int,int>> edges;
for(int i = 0;i<n-1;i++){
int a,b;cin>>a>>b;
a--;b--;
edges.push_back(make_pair(a,b));
links[a].push_back(b);
links[b].push_back(a);
}
root(0,0,-1);
int C;
for(int i = 0;i<m;i++){
int p,c;cin>>p>>c;
C=c;
p--;
auto a = edges[p].first;
auto b = edges[p].second;
if(depth[a]<depth[b])swap(a,b);
peages[c].push_back(a);
val[a].push_back(c);
}
//On calcule la tab de LCA
for(int l=1;l<LOG;l++){
for(int i = 0;i<n;i++){
if(up[i][l-1]==-1){
up[i][l]=-1;
}
up[i][l] = up[up[i][l-1]][l-1];
}
}
for(int i = 0;i<q;i++){
int a,b,x,y;cin>>a>>b>>x>>y;
a--;b--;
int lca = LCA(a,b);
int ans = 0;
if(lca==a){
swap(a,b);
}
set<int> S;
auto f = [&](int l){
for(int j=l;j!=-1 && j!=lca;j=up[j][0])
S.insert(j);
};
f(a);
f(b);
vector<int> vec;
for(auto x:S){
for(auto v:val[x]){
vec.push_back(v);
}
}
sort(vec.begin(),vec.end());
int cnt=0;
for(int j = 0;j<vec.size() && y>=vec[j];j++){
y -= vec[j];
cnt++;
}
if((vec.size()-cnt)>x){
cout<<-1<<'\n';
}else{
cout<<x-(vec.size()-cnt)<<endl;
}
}
return 0;
};
