#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define ld long double
#define pb push_back
#define all(v) begin(v), end(v)
#define pll pair<ll, ll>
#define fi first
#define se second
#define vll vector<ll>
#define mll map<ll, ll>
#define endl '\n'
mt19937_64 rng(chrono::high_resolution_clock().now().time_since_epoch().count());
const ll N = 1e5 + 6, inf = 1e18 + 7, mod = 1e9 + 7;
ll n, m, k, q, s[N], t[N], l[N], b[N], x[N], y[N], L[N], R[N], ans[N];
pll p[N];
vll adj[N];
pll edge[N];
ll tin[N], tout[N], timer = 0, dep[N], li[N][21];
void dfs(ll p, ll u) {
tin[u] = ++timer;
for (ll v : adj[u]) {
if (v == p) continue;
dep[v] = dep[u] + 1;
li[v][0] = u;
for (int j = 1; j <= 20; ++j) li[v][j] = li[li[v][j-1]][j-1];
dfs(u, v);
}
tout[u] = timer;
}
bool is_anc(ll u, ll v) {
return tin[u] <= tin[v] && tout[v] <= tout[u];
}
ll lca(ll u, ll v) {
if (is_anc(u, v)) return u;
if (is_anc(v, u)) return v;
for (int j = 20; j >= 0; --j) {
if (li[u][j] && !is_anc(li[u][j], v)) {
u = li[u][j];
}
}
return li[u][0];
}
struct Fen {
ll bit[N];
void update(ll i, ll val) {
for (; i < N; i += i & -i) bit[i] += val;
}
void range_update(ll l, ll r, ll val) {
update(l, val);
update(r+1, -val);
}
void update_edge(ll i, ll val) {
auto [u, v] = edge[i];
if (dep[u] < dep[v]) swap(u, v);
range_update(tin[u], tout[u], val);
}
ll get(ll i) {
ll ans = 0;
for (; i > 0; i -= i & -i) ans += bit[i];
return ans;
}
ll get_path(ll i) {
return get(tin[s[i]]) + get(tin[t[i]]) - 2*get(tin[l[i]]);
}
void reset() {
fill(bit, bit+N, 0);
}
} f1, f2;
vll v1[N];
void solve() {
cin >> n >> m >> q;
for (int i = 1; i < n; ++i) {
ll x, y;
cin >> x >> y;
adj[x].pb(y);
adj[y].pb(x);
edge[i] = {x, y};
}
dfs(-1, 1);
for (int i = 1; i <= m; ++i) cin >> p[i].se >> p[i].fi;
sort(p+1, p+m+1);
//sort(p+1,p+m+1,greater<>());
for (int i = 1; i <= m; ++i) f2.update_edge(p[i].se, 1);
for (int i = 1; i <= q; ++i) {
cin >> s[i] >> t[i] >> x[i] >> y[i];
l[i] = lca(s[i], t[i]);
b[i] = f2.get_path(i);
//cout << l[i] << " " << b[i] << endl;
L[i] = 0, R[i] = m;
ans[i] = -1;
}
f2.reset();
for (int pbs = 1; pbs <= 20; ++pbs) {
f1.reset();
f2.reset();
for (int i = 0; i <= m; ++i) v1[i].clear();
for (int i = 1; i <= q; ++i) {
if (L[i] <= R[i]) {
ll mid = (L[i] + R[i]) / 2;
v1[mid].pb(i);
}
}
for (int i = 0; i <= m; ++i) {
if (i) {
f1.update_edge(p[i].se, p[i].fi);
f2.update_edge(p[i].se, 1);
}
for (int j : v1[i]) {
ll sum = f1.get_path(j), cnt = f2.get_path(j);
//cout << i << " " << sum << " " << cnt << endl;
if (sum <= y[j]) {
ans[j] = x[j] - (b[j] - cnt);
L[j] = i+1;
} else R[j] = i-1;
}
}
}
for (int i = 1; i <= q; ++i) cout << (ans[i] < 0 ? -1 : ans[i]) << endl;
return;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
if (fopen(".inp", "r")) {
freopen(".inp", "r", stdin);
freopen(".out", "w", stdout);
}
ll tc = 1;
//cin >> tc;
while (tc--) {
solve();
}
return 0;
}
