#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define int long long
#define pii pair<int, int>
#define ff first
#define ss second
#define entire(x) (x).begin(), (x).end()
const int inf = 9e18;
struct DDA {
int n = 1;
vector<int> Tree;
DDA (int N) {
++N; while (n < N) n <<= 1;
Tree.resize(2 * n, 0);
}
void update (int i, int delta){
for (i += n; i > 0; i >>= 1) Tree[i] += delta;
}
int query (int l, int r){ // [l, r]
int res = 0;
for (l += n, r += n; l <= r; l >>= 1, r >>= 1){
if (l & 1) res += Tree[l++];
if (!(r & 1)) res += Tree[r--];
} return res;
}
};
int32_t main(){
ios::sync_with_stdio(false); cin.tie(nullptr);
int n, m, q; cin >> n >> m >> q;
vector<pii> edge(n-1);
vector<vector<int>> adj(n), Adj(n);
for (int i = 0; i < n-1; i++){
int u, v; cin >> u >> v; u--, v--;
Adj[u].push_back(v); Adj[v].push_back(u);
edge[i] = pii{u, v};
}
vector<int> tin(n), tout(n);
int timer = 0, logn = 2 + log2(n);
vector<vector<int>> pi(n, vector<int>(logn, 0));
auto reroot = [&](auto&& self, int s, int parent) -> void{
tin[s] = timer++; pi[s][0] = parent;
for (int i = 1; i < logn; i++) pi[s][i] = pi[pi[s][i-1]][i-1];
for (auto u : Adj[s]) if (u != parent){
adj[s].push_back(u); self(self, u, s);
} tout[s] = timer;
}; reroot(reroot, 0, 0);
while (true) { break; }
auto isAnc = [&](int anc, int u){
return (tin[anc] <= tin[u] and tout[u] <= tout[anc]);
};
auto lca = [&](int u, int v){
if (isAnc(u, v) or isAnc(v, u)) return isAnc(u, v) ? u : v;
for (int i = logn-1; i > -1; i--){
if (!isAnc(pi[u][i], v)) u = pi[u][i];
} return pi[u][0];
};
for (auto& [u, v] : edge) if (isAnc(v, u)) swap(u, v);
vector<pii> t(m);
for (int i = 0; i < m; i++){
int p, c; cin >> p >> c; p--;
int v = edge[p].ss;
t[i] = pii{c, v};
} sort(entire(t));
vector<array<int, 4>> qn(q); // x gold, y silver
for (auto& [u, v, x, y] : qn) cin >> u >> v >> x >> y, u--, v--;
DDA cnt(n), et(n);
auto psum = [&](int u, int v){
int anc = lca(u, v), ea = et.query(0, tin[anc]);
int pu = et.query(0, tin[u]), pv = et.query(0, tin[v]);
return pu + pv - 2 * ea;
};
auto pcnt = [&](int u, int v){
int anc = lca(u, v), ca = cnt.query(0, tin[anc]);
int cu = cnt.query(0, tin[u]), cv = cnt.query(0, tin[v]);
return cu + cv - 2 * ca;
};
auto add = [&](int i){
auto [w, v] = t[i];
et.update(tin[v], +w); et.update(tout[v], -w);
cnt.update(tin[v], +1); cnt.update(tout[v], -1);
};
vector<deque<int>> bs(m);
vector<pii> bound(q, pii{0, m-1});
vector<int> mcost(q, inf), cmin(q, 0);
for (int i = 0; i < q; i++) bs[m/2].push_back(i);
auto reduce = [&](int i, vector<deque<int>>& nbs){
auto [u, v, x, y] = qn[i];
auto& [l, r] = bound[i];
int mid = (l + r + 1) / 2, path = psum(u, v);
if (!(l < r)){ cmin[i] = pcnt(u, v); mcost[i] = path; return;}
if (path <= y) l = mid, cmin[i] = pcnt(u, v), mcost[i] = path;
else r = mid - 1;
mid = (l + r + 1) / 2; nbs[mid].push_back(i);
};
int logm = 2 + log2(m);
for (int depth = 0; depth <= logm; depth++){
vector<deque<int>> nbs(m);
fill(entire(cnt.Tree), 0ll); fill(entire(et.Tree), 0ll);
for (int i = 0; i < m; i++){
add(i); while (!bs[i].empty()) reduce(bs[i].back(), nbs), bs[i].pop_back();
} bs = nbs;
}
fill(entire(cnt.Tree), 0ll); fill(entire(et.Tree), 0ll);
for (int i = 0; i < m; i++) add(i);
vector<int> ans(q);
for (int i = 0; i < q; i++){
auto [u, v, x, y] = qn[i];
if (mcost[i] <= y) ans[i] = pcnt(u, v) - cmin[i];
else ans[i] = pcnt(u, v);
ans[i] = (ans[i] <= x) ? (x - ans[i]) : -1;
}
for (auto val : ans) cout << val << endl;
return 0;
}
