#include "bits/stdc++.h"
using namespace std;
#define int long long
const int maxn = 1e5 + 5;
int n, m, q;
vector<int> g[maxn];
int edge_u[maxn], edge_v[maxn];
int p[maxn];
long long c[maxn];
int s[maxn], t[maxn];
long long x[maxn], y[maxn];
int le[maxn], ri[maxn];
long long res[maxn];
int cur_pos, pos[maxn], head[maxn];
int sz[maxn], h[maxn], par[maxn];
int ord[maxn];
vector<int> cand[maxn];
struct fenwick_tree {
#define gb(x) (x) & (-x)
int n;
vector<long long> bit;
fenwick_tree() {}
fenwick_tree(int n) : n(n), bit(n + 5, 0) {}
void update(int x, long long val) {
for(int i = x; i <= n; i += gb(i)) bit[i] += val;
}
long long get(int x) {
long long ans = 0;
for(int i = x; i > 0; i -= gb(i)) ans += bit[i];
return ans;
}
long long get(int l, int r) {
if(l > r) return 0;
return get(r) - get(l - 1);
}
} fen, fen_cnt;
void pre_dfs(int u, int prev) {
sz[u] = 1;
for(auto v:g[u]) {
if(v == prev) continue;
h[v] = h[u] + 1;
par[v] = u;
pre_dfs(v, u);
sz[u] += sz[v];
}
}
void hld(int u, int prev) {
if(!head[u]) {
head[u] = u;
}
pos[u] = ++cur_pos;
int big_child = -1;
for(auto v:g[u]) {
if(v == prev) continue;
if(big_child == -1 || sz[big_child] < sz[v]) big_child = v;
}
if(big_child != -1) {
head[big_child] = head[u];
hld(big_child, u);
}
for(auto v:g[u]) {
if(v == prev || v == big_child) continue;
hld(v, u);
}
}
void update(int u, long long val) {
fen.update(pos[u], val);
}
void update_cnt(int u) {
fen_cnt.update(pos[u], 1);
}
long long get(int u, int v) {
long long ans = 0;
while(head[u] != head[v]) {
if(h[u] > h[v]) swap(u, v);
ans += fen.get(pos[head[v]], pos[v]);
v = par[head[v]];
}
if(h[u] > h[v]) swap(u, v);
ans += fen.get(pos[u] + 1, pos[v]);
return ans;
}
long long get_cnt(int u, int v) {
long long ans = 0;
while(head[u] != head[v]) {
if(h[u] > h[v]) swap(u, v);
ans += fen_cnt.get(pos[head[v]], pos[v]);
v = par[head[v]];
}
if(h[u] > h[v]) swap(u, v);
ans += fen_cnt.get(pos[u] + 1, pos[v]);
return ans;
}
void solve() {
cin >> n >> m >> q;
for(int i = 1; i < n; ++i) {
int u, v; cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
edge_u[i] = u, edge_v[i] = v;
}
for(int i = 1; i <= m; ++i) {
cin >> p[i] >> c[i];
ord[i] = i;
}
for(int i = 1; i <= q; ++i) {
cin >> s[i] >> t[i] >> x[i] >> y[i];
le[i] = 1, ri[i] = m;
}
par[1] = h[1] = 1;
pre_dfs(1, 0);
hld(1, 0);
for(int i = 1; i < n; ++i) {
if(par[edge_u[i]] == edge_v[i]) swap(edge_u[i], edge_v[i]);
}
sort(ord + 1, ord + m + 1, [](const int &x, const int &y) -> bool {
return (c[x] != c[y] ? c[x] < c[y] : x < y);
});
while(1) {
bool exist = 0;
for(int i = 1; i <= q; ++i) {
if(le[i] <= ri[i]) {
int mid = (le[i] + ri[i]) / 2;
cand[mid].push_back(i);
exist = 1;
}
}
if(!exist) break;
fen = fenwick_tree(n + 1);
for(int mid = 1; mid <= m; ++mid) {
update(edge_v[p[ord[mid]]], c[ord[mid]]);
for(auto i:cand[mid]) {
long long im_hungry = get(s[i], t[i]);
if(im_hungry <= y[i]) {
res[i] = mid;
le[i] = mid + 1;
}
else {
ri[i] = mid - 1;
}
}
cand[mid].clear();
}
}
for(int i = 1; i <= q; ++i) {
cerr << res[i] << " \n"[i == q];
cand[res[i]].push_back(i);
}
fen_cnt = fenwick_tree(n + 1);
for(int i = m; i >= 0; --i) {
for(auto j:cand[i]) {
res[j] = x[j] - get_cnt(s[j], t[j]);
}
if(i) update_cnt(edge_v[p[ord[i]]]);
}
for(int i = 1; i <= q; ++i) {
cout << (res[i] < 0 ? -1 : res[i]) << '\n';
}
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
