/*
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,fma,bmi,bmi2,sse4.2,popcnt,lzcnt")
*/
#include <bits/stdc++.h>
#define taskname ""
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define int long long
#define i64 long long
#define pb push_back
#define ff first
#define ss second
#define isz(x) (int)x.size()
using namespace std;
const int mxN = 1e5 + 5;
const int mod = 1e9 + 7;
const int LOG = 20;
const i64 oo = 1e18;
void adds(pair<i64, int> &val, pair<i64, int> nval) {
val.ff += nval.ff;
val.ss += nval.ss;
}
struct FenwickTree {
int n;
vector<pair<i64, int>> data;
FenwickTree() {};
FenwickTree(int n) : n(n), data(n + 10) {}
void update(int idx, pair<i64, int> val) {
while (idx <= n) {
adds(data[idx], val);
idx += idx & -idx;
}
}
pair<i64, int> get(int idx) {
pair<i64, int> res = {0, 0};
while (idx) {
adds(res, data[idx]);
idx -= idx & -idx;
}
return res;
}
} fenw;
struct Checkpoint {
int p, c;
Checkpoint(int p, int c) : p(p), c(c) {}
bool operator < (const Checkpoint &cp) const {
return c < cp.c;
}
};
struct Query {
int s, t, x, y;
Query(int s, int t, int x, int y) : s(s), t(t), x(x), y(y) {}
};
int n, m, q, ans[mxN];
vector<Query> qq;
vector<Checkpoint> cp;
pair<int, int> edges[mxN];
vector<pair<int, int>> G[mxN];
int tin[mxN], tout[mxN], ap[mxN], par[mxN], dep[mxN], cnt_edges[mxN], h[mxN], tdfs, ecnt;
pair<int, int> euler[LOG][2 * mxN];
int ptr_pbs = -1;
void dfs(int v, int p) {
tin[v] = ++tdfs;
dep[v] = dep[p] + 1;
par[v] = p;
euler[0][++ecnt] = {dep[v], v};
ap[v] = ecnt;
for (auto [u, eidx] : G[v]) if (u != p) {
h[u] = h[v] + cnt_edges[eidx];
dfs(u, v);
euler[0][++ecnt] = {dep[v], v};
}
tout[v] = tdfs;
}
void build_euler() {
for (int i = 1, p = 1; (p << 1) <= ecnt; ++i, p <<= 1) {
for (int j = 1; j + (p << 1) - 1 <= ecnt; ++j) {
euler[i][j] = min(euler[i - 1][j], euler[i - 1][j + p]);
}
}
}
int LCA(int u, int v) {
int l = ap[u], r = ap[v];
if (l > r) swap(l, r);
int len = r - l + 1, lg_len = 31 - __builtin_clz(len);
return min(euler[lg_len][l], euler[lg_len][r - (1 << lg_len) + 1]).ss;
}
void add(int cpidx) {
auto [p, c] = cp[cpidx];
auto [u, v] = edges[p];
if (dep[u] < dep[v]) swap(u, v);
fenw.update(tin[u], {c, 1});
fenw.update(tout[u] + 1, {-c, -1});
}
void del(int cpidx) {
auto [p, c] = cp[cpidx];
auto [u, v] = edges[p];
if (dep[u] < dep[v]) swap(u, v);
fenw.update(tin[u], {-c, -1});
fenw.update(tout[u] + 1, {c, 1});
}
void pbs(int l, int r, vector<int> &qq_idx) {
if (l > r or qq_idx.empty()) return;
int mid = (l + r) >> 1;
while (ptr_pbs < mid) add(++ptr_pbs);
while (ptr_pbs > mid) del(ptr_pbs--);
vector<int> qql, qqr;
for (int idx : qq_idx) {
auto [s, t, x, y] = qq[idx];
int lca = LCA(s, t);
pair<i64, int> total_silver = {0, 0};
adds(total_silver, fenw.get(tin[s]));
adds(total_silver, fenw.get(tin[t]));
auto cur = fenw.get(tin[lca]); cur.ff *= -2, cur.ss *= -2;
adds(total_silver, cur);
if (total_silver.ff <= x) {
ans[idx] = max(ans[idx], y - (h[s] + h[t] - 2 * h[lca] - total_silver.ss));
qqr.emplace_back(idx);
}
else {
qql.emplace_back(idx);
}
}
pbs(l, mid - 1, qql);
pbs(mid + 1, r, qqr);
}
void solve() {
cin >> n >> m >> q;
fenw = FenwickTree(n);
for (int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
G[u].emplace_back(v, i);
G[v].emplace_back(u, i);
edges[i] = {u, v};
}
for (int i = 1; i <= m; ++i) {
int p, c;
cin >> p >> c;
cp.emplace_back(p, c);
cnt_edges[p]++;
}
sort(all(cp));
for (int i = 1; i <= q; ++i) {
int s, t, x, y;
cin >> s >> t >> y >> x;
qq.emplace_back(s, t, x, y);
ans[i - 1] = -1;
}
dfs(1, 0);
build_euler();
vector<int> qq_idx(q); iota(all(qq_idx), 0);
pbs(-1, m - 1, qq_idx);
for (int i = 0; i < q; ++i)
cout << ans[i] << "\n";
}
signed main() {
#ifndef CDuongg
if(fopen(taskname".inp", "r"))
assert(freopen(taskname".inp", "r", stdin)), assert(freopen(taskname".out", "w", stdout));
#else
freopen("bai3.inp", "r", stdin);
freopen("bai3.out", "w", stdout);
auto start = chrono::high_resolution_clock::now();
#endif
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1; //cin >> t;
while(t--) solve();
#ifdef CDuongg
auto end = chrono::high_resolution_clock::now();
// cout << "\n"; for(int i = 1; i <= 100; ++i) cout << '=';
// cout << "\nExecution time: " << chrono::duration_cast<chrono::milliseconds> (end - start).count() << "[ms]" << endl;
// cout << "Check array size pls sir" << endl;
#endif
}
