#include <bits/stdc++.h>
#define int long long
#define sz(a) (int)a.size()
const int LOG=20;
using namespace std;
vector<int> dist;
vector<int> depth;
vector<int> sum;
vector<vector<int>> parent;
vector<vector<pair<int,int>>> child;
vector<vector<pair<int,int>>> neigh;
vector<pair<int,pair<int,int>>> edges;
vector<int> v;
void make_tree(int x, int p){
parent[x][0]=p;
depth[x]=depth[p]+1;
for (auto u : neigh[x])
{
if(u.first==p) continue;
sum[u.first]+=u.second;
make_tree(u.first,x);
child[x].push_back({u.first,u.second});
sum[x]+=sum[u.first];
}
}
int lca(int a, int b){
if(depth[a]>depth[b]) swap(a,b);
int d=depth[b]-depth[a];
for (int j = LOG-1; j >= 0; j--) {
if(d&(1<<j)) b=parent[b][j];
}
if(a==b) return a;
for (int j = LOG-1; j >= 0; j--) {
if(parent[a][j]!=parent[b][j]) {
a=parent[a][j];
b=parent[b][j];
}
}
return parent[a][0];
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n,m,q; cin >> n >> m >> q;
edges.resize(n-1);
depth.resize(n);
sum.resize(n);
dist.resize(n);
child.resize(n);
neigh.resize(n);
parent.resize(n, vector<int>(LOG, 0));
int totalSUM=0;
for (int i = 0; i < n-1; i++)
{
int a,b; cin >> a >> b;
edges[i]={0,{a-1,b-1}};
}
for (int i = 0; i < m; i++){
int p,c; cin >> p >> c;
edges[p-1].first+=c;
totalSUM+=c;
}
for (int i = 0; i < n-1; i++){
int a=edges[i].second.first,b=edges[i].second.second,c=edges[i].first;
neigh[a].push_back({b,c});
neigh[b].push_back({a,c});
if(c>0) v.push_back(c);
}
make_tree(0,0);
depth[0]=0;
for (int j = 1; j < LOG; j++) for (int i = 0; i < n; i++) parent[i][j]=parent[parent[i][j-1]][j-1];
sort(v.begin(),v.end());
for (int i = 1; i < sz(v); i++) v[i]+=v[i-1];
while(q--)
{
int s,t,x,y; cin >> s >> t >> x >> y;
int lc=lca(s-1,t-1);
int sm=sum[parent[lc][0]]-sum[t-1]-sum[s-1];
int lb=lower_bound(v.begin(),v.end(), sm+y)-v.begin();
int u=(sz(v))-lb;
if(u>x) cout << -1 << "\n";
else cout << u << "\n";
}
return 0;
}
