#include <bits/stdc++.h>
using namespace std;
#define int long long
using namespace std;
const int LOG = 19, inf = 1e18;
vector<vector<int>> adj, up;
vector<pair<int, int>> edges, queries, check, coin;
vector<int> in_time, out_time;
int timer = 0;
struct Fenwick{
int n; vector<int> tree;
Fenwick(int _n) : n(_n + 5), tree(_n + 5, 0) {}
void _update(int pos, int val){
for(pos++; pos < n; pos += pos & (-pos)) tree[pos] += val;
} int query(int pos){
int res = 0;
for(pos++; pos > 0; pos -= pos & (-pos)) res += tree[pos];
return res;
} void update(int in, int out, int val){
_update(in, val), _update(out + 1, -val);
}
};
void dfs(int u, int par){
in_time[u] = ++timer;
up[u][0] = par;
for(int i = 1; i < LOG; i++)
if(up[u][i - 1] != -1) up[u][i] = up[up[u][i - 1]][i - 1];
for(const int &v : adj[u])
if(v != par) dfs(v, u);
out_time[u] = timer;
}
bool is_ances(int u, int v){
return in_time[u] <= in_time[v] && out_time[v] <= out_time[u];
}
int _lca(int u, int v){
if(is_ances(u, v)) return u;
if(is_ances(v, u)) return v;
for(int i = LOG - 1; i >= 0; i--)
if(up[u][i] != -1 &&!is_ances(up[u][i], v)) u = up[u][i];
return up[u][0];
}
void solve(){
int n, m, q; cin >> n >> m >> q;
adj.resize(n + 1), up.resize(n + 1, vector<int> (LOG, -1));
in_time.resize(n + 1), out_time.resize(n + 1);
for(int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
edges.push_back({u, v});
adj[u].push_back(v), adj[v].push_back(u);
} for(int i = 0; i < m; i++){
int p, c; cin >> p >> c;
check.push_back({p, c});
} sort(check.begin(), check.end(), [&](pair<int, int> a, pair<int, int> b){
if(a.second == b.second) return a.first < b.first;
return a.second < b.second;
});
dfs(1, -1);
for(int i = 1; i < n; i++){
if(is_ances(edges[i - 1].second, edges[i - 1].first)) swap(edges[i - 1].first, edges[i - 1].second);
} vector<pair<int, int>> queries(q);
vector<int> lca(q);
for(int i = 0; i < q; i++){
int g, s;
cin >> queries[i].first >> queries[i].second >> g >> s;
coin.push_back({g, s});
lca[i] = _lca(queries[i].first, queries[i].second);
} vector<int> le(q, 0), ri(q, m), res(q, inf);
bool cont = true;
int turn = 0;
while(cont){
turn++;
cont = false;
vector<vector<int>> bucket(m + 1);
for(int i = 0; i < q; i++){
if(le[i] != ri[i]){
cont = true;
int mid = (le[i] + ri[i] + 1) / 2;
bucket[mid].push_back(i);
}
} Fenwick bit_sil(timer), bit_gol(timer);
for(int i = 0; i <= m; i++){
if(i != 0){
const auto &[p, c] = check[i - 1];
bit_sil.update(in_time[edges[p - 1].second], out_time[edges[p - 1].second], c);
bit_gol.update(in_time[edges[p - 1].second], out_time[edges[p - 1].second], 1);
} for(const int &q : bucket[i]){
const auto &[u, v] = queries[q];
int l = lca[q];
int sil = bit_sil.query(in_time[u]) + bit_sil.query(in_time[v]) - 2 * bit_sil.query(in_time[l]);
int gol = bit_gol.query(in_time[u]) + bit_gol.query(in_time[v]) - 2 * bit_gol.query(in_time[l]);
if(sil <= coin[q].second) le[q] = i, res[q] = gol;
else ri[q] = i - 1;
}
}
} Fenwick bit(timer);
for(int i = 0; i < m; i++){
const auto &[p, c] = check[i];
int idx = edges[p - 1].second;
bit.update(in_time[idx], out_time[idx], 1);
} for(int i = 0; i < q; i++){
const auto &[u, v] = queries[i];
if(res[i] == inf) res[i] = 0;
cout << max((long long)-1, coin[i].first - (bit.query(in_time[u]) + bit.query(in_time[v]) - 2 * bit.query(in_time[lca[i]]) - res[i])) << "\n";
}
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int test;
test = 1;
//cin >> test;
while(test--) solve();
}
