#include <bits/stdc++.h>
#define int long long
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
using namespace std;
vector<vector<pair<int,int>>> neigh;
vector<vector<pair<int,pair<int,int>>>> chk;
vector<int> s,e;
vector<int> tour;
void dfs(int x, int p){
for (auto u : neigh[x])
{
if(u.first==p) continue;
tour.push_back(u.second);
s[u.first]=sz(tour);
dfs(u.first,x);
e[u.first]=sz(tour);
tour.push_back(u.second);
}
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n,m,q; cin >> n >> m >> q;
neigh.resize(n);
s.resize(n);
e.resize(n);
chk.resize(n-1);
for (int i = 0; i < n-1; i++)
{
int a,b; cin >> a >> b; a--; b--;
neigh[a].push_back({b,i});
neigh[b].push_back({a,i});
}
vector<pair<int,int>> s_chk;
for (int i = 0; i < m; i++)
{
int p, c; cin >> p >> c; p--;
s_chk.push_back({c,p});
}
sort(all(s_chk));
int sq=sqrt(n)*2;
int _i=0, _j=0;
while(_i+sq*_j<m){
auto p=s_chk[_i+sq*_j];
chk[p.second].push_back({p.first, {_i, _j}});
_i++;
if(_i==sq) _j++, _i=0;
}
dfs(0,-1);
vector<vector<pair<int,int>>> query_block(sq);
vector<pair<pair<int,int>, pair<int,int>>> query(q);
vector<pair<int,int>> qs(q);
vector<int> ans(q);
for (int i = 0; i < q; i++)
{
int a,b; cin >> a >> b; a--; b--;
int x,y; cin >> x >> y;
if(s[a]>s[b]) swap(a,b);
if(e[a]>e[b]) a=s[a], b=s[b]-1;
else a=e[a], b=s[b]-1;
query[i]={{a,b}, {x,y}};
qs[i]={a,i};
}
sort(all(qs));
int sqm=0;
_j=0;
_i=0;
for (int i = 0; i < sz(tour); i++)
{
if(sqm+sz(chk[tour[i]])>sq) _j++, sqm=0;
sqm+=sz(chk[tour[i]]);
while(_i<q&&qs[_i].first==i){
query_block[_j].push_back({query[qs[_i].second].first.second,qs[_i].second});
_i++;
}
}
for (int i = 0; i < sz(query_block); i++) sort(all(query_block[i]));
for (int j = 0; j < sq; j++)
{
vector<bool> used(n-1,0);
vector<int> sm_block(sq,0);
vector<int> cnt_block(sq,0);
vector<vector<int>> chk_block(sq,vector<int>(sq));
int l=0;
int r=-1;
int tot=0;
for (int i = 0; i < sz(query_block[j]); i++)
{
int indx=query_block[j][i].second;
int ql=query[indx].first.first;
int qr=query[indx].first.second;
int cx=query[indx].second.first;
int cy=query[indx].second.second;
vector<int> add;
vector<int> rem;
while(r<qr){
r++;
int x=tour[r];
if(used[x]) rem.push_back(x);
else add.push_back(x);
used[x]=!used[x];
}
while(l<ql){
int x=tour[l];
if(used[x]) rem.push_back(x);
else add.push_back(x);
used[x]=!used[x];
l++;
}
while(l>ql){
l--;
int x=tour[l];
if(used[x]) rem.push_back(x);
else add.push_back(x);
used[x]=!used[x];
}
for (auto x : add)
{
for (auto u : chk[x])
{
sm_block[u.second.second]+=u.first;
cnt_block[u.second.second]++;
chk_block[u.second.second][u.second.first]+=u.first;
tot++;
}
}
for (auto x : rem)
{
for (auto u : chk[x])
{
sm_block[u.second.second]-=u.first;
cnt_block[u.second.second]--;
chk_block[u.second.second][u.second.first]-=u.first;
tot--;
}
}
int csm=0;
int cnt=0;
int k=0;
while(k<sq){
if(csm+sm_block[k]>cy) break;
csm+=sm_block[k];
cnt+=cnt_block[k];
k++;
}
for (int _k = 0; _k < sq && k<sq; _k++)
{
if(chk_block[k][_k]+csm>cy) break;
cnt+=(chk_block[k][_k]>0);
csm+=chk_block[k][_k];
}
cx-=tot-cnt;
ans[indx]=max(-1LL,cx);
}
}
for (int i = 0; i < q; i++) cout << ans[i] << "\n";
return 0;
}
