#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define fastio ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
typedef pair<int, int> pii;
const int mod = 2147483647;
const int inf = 1e9 + 7;
const int N = 1e5 + 5;
int h[N], tin[N], tout[N], t = 0;
int up[N][20];
vector<int> adj[N];
void dfs(int u, int par){
tin[u] = ++t;
for(int v : adj[u]){
if(v == par) continue;
h[v] = h[u] + 1;
up[v][0] = u;
dfs(v, u);
}
tout[u] = t;
}
int lca(int u, int v){
if(h[u] < h[v]) swap(u, v);
int diff = h[u] - h[v];
for(int i = 18; i >= 0; i--){
if(diff >= (1 << i)){
diff -= (1 << i);
u = up[u][i];
}
}
if(u == v) return u;
for(int i = 18; i >= 0; i--){
if(up[u][i] != up[v][i]){
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
struct Fenwick{
vector<ll> f; int n;
Fenwick(int _n){
n = _n;
f.resize(n + 5, 0);
}
void update_point(int u, int val){
for(; u < N; u += u&(-u)){
f[u] += val;
}
}
void update_range(int u, int v, ll val){
update_point(u, val);
update_point(v + 1, -val);
}
ll get(int u){
ll ans = 0;
for(; u > 0; u -= u&(-u)){
ans += f[u];
}
return ans;
}
};
bool is_ances(int u, int v){
return tin[u] <= tin[v] && tout[v] <= tout[u];
}
vector<int> bucket[N];
int leftb[N], rightb[N], ans[N];
pair<ll, int> p[N];
int S[N], T[N]; ll X[N], Y[N];
signed main(){
fastio
int n, m, q; cin >> n >> m >> q;
vector<pii> edges;
for(int i = 1; i < n; i++){
int u, v; cin >> u >> v;
adj[u].pb(v);
adj[v].pb(u);
edges.pb({u, v});
}
for(int i = 1; i <= m; i++){
int x; ll y; cin >> x >> y;
p[i] = {y, x};
}
h[1] = 0;
dfs(1, 1);
for(int i = 0; i < edges.size(); i++){
if(is_ances(edges[i].se, edges[i].fi)) swap(edges[i].fi, edges[i].se);
}
up[1][0] = 1;
for(int i = 1; i <= 18; i++){
for(int j = 1; j <= n; j++) up[j][i] = up[up[j][i - 1]][i - 1];
}
for(int i = 1; i <= q; i++){
cin >> S[i] >> T[i] >> X[i] >> Y[i];
leftb[i] = 0; rightb[i] = m;
ans[i] = inf;
}
sort(p + 1, p + m + 1);
while(true){
bool ck = false;
for(int i = 1; i <= q; i++){
if(leftb[i] < rightb[i]){
int mid = (leftb[i] + rightb[i] + 1) >> 1;
bucket[mid].pb(i);
ck = true;
}
}
if(!ck) break;
Fenwick cost_tree(N), count_tree(N);
for(int i = 0; i <= m; i++){
if(i > 0){
int u = edges[p[i].se - 1].se;
cost_tree.update_range(tin[u], tout[u], p[i].fi);
count_tree.update_range(tin[u], tout[u], 1);
}
for(int idx : bucket[i]){
ll gold_needed = count_tree.get(tin[S[idx]]) + count_tree.get(tin[T[idx]]) - 2 * count_tree.get(tin[lca(S[idx], T[idx])]);
ll silver_needed = cost_tree.get(tin[S[idx]]) + cost_tree.get(tin[T[idx]]) - 2 * cost_tree.get(tin[lca(S[idx], T[idx])]);
if(silver_needed <= Y[idx]){
ans[idx] = gold_needed;
leftb[idx] = i;
}
else rightb[idx] = i - 1;
}
bucket[i].clear();
}
}
Fenwick bit(N);
for(int i = 1; i <= m; i++){
int v = edges[p[i].se - 1].se;
bit.update_range(tin[v], tout[v], 1);
}
for(int i = 1; i <= q; i++){
if(ans[i] >= inf) ans[i] = 0;
cout << max((ll)-1, X[i] - (bit.get(tin[S[i]]) + bit.get(tin[T[i]]) - 2 * bit.get(tin[lca(S[i], T[i])]) - ans[i])) << '\n';
}
return 0;
}
