#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e5 + 2;
const int M = 20 * N;
const int inf = 1e9;
vector<pair<int, int>> g[N];
int par[N][17], in[N], out[N], tsz, psz;
void Dfs(int s, int e) {
par[s][0] = e;
for (int i = 1; i < 17; i++) par[s][i] = par[par[s][i - 1]][i - 1];
in[s] = ++tsz;
for (auto u : g[s]) {
if (u.first != e) {
Dfs(u.first, s);
}
}
out[s] = tsz;
}
bool Ancestor(int u, int v) {
return in[u] <= in[v] && out[v] <= out[u];
}
int Lca(int u, int v) {
if (Ancestor(u, v)) return u;
if (Ancestor(v, u)) return v;
for (int i = 16; i >= 0; i--) {
if (par[u][i] && !Ancestor(par[u][i], v)) u = par[u][i];
}
return par[u][0];
}
vector<pair<int, int>> dat[N];
vector<int> order, inv;
ll st[M];
int lc[M], rc[M], cnt[M], root[N], uk;
map<int, int> gde;
void Add(int &c, int pc, int l, int r, int pos, int x, int y) {
c = ++tsz; st[c] = st[pc] + x; lc[c] = lc[pc]; rc[c] = rc[pc]; cnt[c] = cnt[pc] + y;
if (l == r) return;
int mid = l + r >> 1;
if (pos <= mid) Add(lc[c], lc[pc], l, mid, pos, x, y);
else Add(rc[c], rc[pc], mid + 1, r, pos, x, y);
}
void Find(int a, int b, int c, int l, int r, ll s) {
ll S = st[a] + st[b] - 2 * st[c];
int C = cnt[a] + cnt[b] - 2 * cnt[c];
if (l == r) {
if (S <= s) uk -= C;
return;
}
int mid = l + r >> 1;
ll Sl = st[lc[a]] + st[lc[b]] - 2 * st[lc[c]];
int Cl = cnt[lc[a]] + cnt[lc[b]] - 2 * cnt[lc[c]];
if (Sl < s) {
uk -= Cl;
Find(rc[a], rc[b], rc[c], mid + 1, r, s - Sl);
}
else Find(lc[a], lc[b], lc[c], l, mid, s);
}
void Dfs1(int s, int e) {
for (auto u : g[s]) {
if (u.first == e) continue;
root[u.first] = root[s];
int nesto = u.second;
for (int i = 0; i < dat[nesto].size(); i++) {
auto uu = dat[nesto][i];
Add(root[u.first], root[u.first], 0, psz, inv[uu.second], uu.first, 1);
}
Dfs1(u.first, s);
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n, m, q;
cin >> n >> m >> q;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
g[u].push_back({v, i});
g[v].push_back({u, i});
}
Dfs(1, 0);
vector<int> vvv(m);
for (int i = 0; i < m; i++) {
int u;
cin >> u >> vvv[i];
dat[u].push_back({vvv[i], i});
}
order.resize(m);
inv.resize(m);
iota(order.begin(), order.end(), 0);
sort(order.begin(), order.end(), [&] (int i, int j) {
return vvv[i] < vvv[j];
});
for (int i = 0; i < m; i++) inv[order[i]] = i;
psz = m - 1;
tsz = 0;
Dfs1(1, 0);
while (q--) {
int s, t, x; ll y;
cin >> s >> t >> x >> y;
int lca = Lca(s, t);
uk = cnt[root[s]] + cnt[root[t]] - 2 * cnt[root[lca]];
Find(root[s], root[t], root[lca], 0, psz, y);
cout << max(x - uk, -1) << en;
}
return 0;
}
