#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,popcnt,sse4,abm")
#include <bits/stdc++.h>
using namespace std;
#ifdef WAIMAI
#define debug(HEHE...) cout << "[" << #HEHE << "] : ", dout(HEHE)
void dout() {cout << '\n';}
template<typename T, typename...U>
void dout(T t, U...u) {cout << t << (sizeof...(u) ? ", " : ""), dout(u...);}
#else
#define debug(...) 7122
#endif
#define ll long long
#define Waimai ios::sync_with_stdio(false), cin.tie(0)
#define FOR(x,a,b) for (int x = a, I = b; x <= I; x++)
#define pb emplace_back
#define F first
#define S second
const int SIZE = 2e5 + 5;
const int TSIZ = (__lg(SIZE) + 4) * SIZE;
int n, m, q;
pair<int, int> a[SIZE];
vector<int> adj[SIZE], op[SIZE];
struct Node {
int cnt, ls, rs;
ll sum;
Node() {}
Node(int cnt, ll sum) : cnt(cnt), sum(sum), ls(0), rs(0) {}
Node operator + (const Node &o) const {
return Node(cnt + o.cnt, sum + o.sum);
}
Node operator - (const Node &o) const {
return Node(cnt - o.cnt, sum - o.sum);
}
} node[TSIZ];
int sz, root[SIZE];
void upd(int &pos, int l, int r, int p) {
node[++sz] = node[pos];
pos = sz;
node[pos].cnt++;
node[pos].sum += a[p].F;
if (l == r) return;
int mid = (l + r) / 2;
if (p <= mid) upd(node[pos].ls, l, mid, p);
else upd(node[pos].rs, mid + 1, r, p);
}
Node que(int tl, int tr, int l, int r, int L, int R) {
if (l == L && r == R) return node[tr] - node[tl];
int mid = (L + R) / 2;
Node &nl = node[tl], &nr = node[tr];
if (r <= mid) return que(nl.ls, nr.ls, l, r, L, mid);
if (l > mid) return que(nl.rs, nr.rs, l, r, mid + 1, R);
return que(nl.ls, nr.ls, l, mid, L, mid) + que(nl.rs, nr.rs, mid + 1, r, mid + 1, R);
}
int w[SIZE], son[SIZE], dep[SIZE], pa[SIZE], top[SIZE];
void dfs1(int pos) {
w[pos] = 1;
for (int np : adj[pos]) if (np != pa[pos]) {
dep[np] = dep[pos] + 1;
pa[np] = pos;
dfs1(np);
w[pos] += w[np];
if (w[np] > w[son[pos]]) son[pos] = np;
}
}
void dfs2(int pos) {
if (top[pos] != 0) root[pos] = root[pa[pos]];
else top[pos] = pos;
for (int i : op[pos]) upd(root[pos], 1, m, i);
if (son[pos]) {
top[son[pos]] = top[pos];
dfs2(son[pos]);
}
for (int np : adj[pos]) if (np != pa[pos] && np != son[pos]) {
dfs2(np);
}
}
int que_cnt(int a, int b) {
int cnt = 0;
while (true) {
if (top[a] == top[b]) {
if (dep[a] > dep[b]) swap(a, b);
int tl = (a == top[a] ? 0 : root[pa[a]]), tr = root[b];
cnt += node[tr].cnt - node[tl].cnt;
break;
}
if (dep[top[a]] < dep[top[b]]) swap(a, b);
cnt += node[root[a]].cnt;
a = pa[top[a]];
}
return cnt;
}
int cal(int r, int a, int b, ll lim) {
if (r == 0) return 0;
int cnt = 0;
ll sum = 0;
while (sum <= lim) {
if (top[a] == top[b]) {
if (dep[a] > dep[b]) swap(a, b);
int tl = (a == top[a] ? 0 : root[pa[a]]), tr = root[b];
Node nd = que(tl, tr, 1, r, 1, m);
cnt += nd.cnt, sum += nd.sum;
break;
}
if (dep[top[a]] < dep[top[b]]) swap(a, b);
Node nd = que(0, root[a], 1, r, 1, m);
cnt += nd.cnt, sum += nd.sum;
a = pa[top[a]];
}
if (sum > lim) return -1;
return cnt;
}
void solve() {
cin >> n >> m >> q;
FOR (i, 1, n - 1) {
int a, b;
cin >> a >> b;
adj[a].pb(n + i), adj[n + i].pb(a);
adj[b].pb(n + i), adj[n + i].pb(b);
}
FOR (i, 1, m) {
auto &[val, p] = a[i];
cin >> p >> val;
p += n;
}
sort(a + 1, a + m + 1);
FOR (i, 1, m) op[a[i].S].pb(i);
dep[1] = 1, dfs1(1), dfs2(1);
while (q--) {
int a, b, x;
ll y;
cin >> a >> b >> x >> y;
int l = 0, r = m, k = que_cnt(a, b);
while (l < r) {
int mid = (l + r) / 2 + 1;
if (cal(mid, a, b, y) >= 0) l = mid;
else r = mid - 1;
}
int d = cal(l, a, b, y);
if (x < k - d) cout << "-1\n";
else cout << x - (k - d) << '\n';
}
}
int main() {
Waimai;
solve();
}
