// na hanooz omidi vjood dare... hanooz ye karayi hast ke bknm :)
#include <bits/stdc++.h>
using namespace std;
#define debug(x) cerr << "(" << (#x) << "): " << (x) << endl;
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second
#define mp make_pair
#define pb push_back
typedef long long ll;
const int maxn5 = 1e5 + 10;
const int lg = 20;
int ti = 3, st[maxn5], ft[maxn5], h[maxn5];
int hcnt[maxn5], cnt[maxn5], s[maxn5], t[maxn5];
int par[lg][maxn5], a[maxn5], b[maxn5], c[maxn5];
int lo[maxn5], hi[maxn5];
ll x[maxn5], y[maxn5], mx[maxn5];
pair <int, int> p[maxn5];
vector <int> req[maxn5];
vector <pair<int, int>> adj[maxn5];
pair <ll, int> operator +(pair <ll, int> a, pair <ll, int> b){
return mp(a.fi + b.fi, a.se + b.se);
}
pair <ll, int> operator -(pair <ll, int> a, pair <ll, int> b){
return mp(a.fi - b.fi, a.se - b.se);
}
pair <ll, int> operator *(int a, pair <ll, int> b){
return mp(a * b.fi, a * b.se);
}
namespace fen{
pair <ll, int> fen[maxn5];
void clear(){
memset(fen, 0, sizeof fen);
}
pair <ll, int> get(int id){
pair<ll, int> ret = {0, 0};
for(; id; id -= id & -id)
ret = ret + fen[id];
return ret;
}
void add(int id, pair <ll, int> val){
for(; id < maxn5; id += id & -id)
fen[id] = fen[id] + val;
}
void add(int l, int r, ll val){
//debug("Adding ");
//debug(l);
//debug(r);
//debug(val);
add(l, mp(val, 1));
add(r + 1, mp(-val, -1));
}
}
int lca(int a, int b){
if(h[a] < h[b])
swap(a, b);
int d = h[a] - h[b];
for(int i = 0; i < lg; i++) if((d >> i)&1)
a = par[i][a];
if(a == b)
return a;
for(int i = lg - 1; i >= 0; i--) if(par[i][a] != par[i][b]){
a = par[i][a];
b = par[i][b];
}
return par[0][a];
}
void dfs_lca(int v){
for(int i = 1; i < lg && par[i - 1][v] != -1; i++)
par[i][v] = par[i - 1][par[i - 1][v]];
st[v] = ++ti;
for(auto [u, id] : adj[v]) if(u != par[0][v]){
h[u] = h[v] + 1;
hcnt[u] = hcnt[v] + cnt[id];
par[0][u] = v;
dfs_lca(u);
}
ft[v] = ti;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
int n, m, q; cin >> n >> m >> q;
for(int i = 0; i < n - 1; i++){
cin >> a[i] >> b[i];
a[i]--; b[i]--;
adj[a[i]].pb({b[i], i});
adj[b[i]].pb({a[i], i});
}
for(int i = 0; i < m; i++){
cin >> p[i].se >> p[i].fi;
p[i].se--;
cnt[p[i].se]++;
}
sort(p, p + m);
memset(par, -1, sizeof par);
dfs_lca(0);
for(int i = 0; i < n - 1; i++)
if(h[a[i]] > h[b[i]])
swap(a[i], b[i]);
memset(lo, -1, sizeof lo);
fill(hi, hi + q + 4, m);
for(int i = 0; i < q; i++){
cin >> s[i] >> t[i] >> x[i] >> y[i];
s[i]--; t[i]--;
c[i] = lca(s[i], t[i]);
}
bool con = true;
while(con){
con = false;
fen::clear();
for(int i = 0; i < q; i++) if(hi[i] - lo[i] > 1){
con = true;
req[(hi[i] + lo[i]) >> 1].pb(i);
}
for(int i = 0; i < m; i++){
fen::add(st[b[p[i].se]], ft[b[p[i].se]], p[i].fi);
//debug(b[p[i].se]);
for(auto id : req[i]){
//debug(st[s[id]]);
//debug(st[t[id]]);
//debug(fen::get(st[s[id]]).se);
//debug(fen::get(st[t[id]]).se);
pair <ll, int> val = fen::get(st[s[id]]) + fen::get(st[t[id]]) - (2 * fen::get(st[c[id]]));
if(val.fi <= y[id]){
//debug(i);
//debug(id);
//debug(val.fi);
//debug(val.se);
lo[id] = i;
mx[id] = val.se;
}
else
hi[id] = i;
}
req[i].clear();
}
}
for(int i = 0; i < q; i++){
//debug(mx[i]);
cout << max(-1ll, x[i] - (hcnt[s[i]] + hcnt[t[i]] - 2 * hcnt[c[i]] - mx[i])) << '\n';
}
}
