#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
using namespace std;
struct fenwick {
int n;
vector<pair<int, int>> fen;
fenwick(int n) : n(n) {
fen = vector<pair<int, int>>(n + 5);
}
pair<int, int> merge(pair<int, int> a, pair<int, int> b) {
pair<int, int> ret = {a.fi + b.fi, a.se + b.se};
return ret;
}
void add(int x, int val) {
++x;
for(;x <= n + 2; x += x & -x) fen[x].fi += val, fen[x].se += 1;
}
pair<int, int> get(int x) {
pair<int, int> res = {0ll, 0ll};
for (;x > 0; x -= x & -x) res = merge(res, fen[x]);
return res;
}
pair<int, int> get(int l, int r) {
++l; ++r;
pair<int, int> vr = get(r), vl = get(l - 1);
return {vr.fi - vl.fi, vr.se - vl.se};
}
};
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n, m, q;
cin >> n >> m >> q;
vector<int> a(n - 1), b(n - 1);
vector<vector<int>> v(n);
for (int i = 0; i < n - 1; i++) {
cin >> a[i] >> b[i];
--a[i]; --b[i];
v[a[i]].push_back(b[i]);
v[b[i]].push_back(a[i]);
}
vector<pair<int, int>> cp; // checkpoint
for (int i = 0; i < m; i++) {
int p, c;
cin >> p >> c;
--p;
cp.push_back({p, c});
}
sort(cp.begin(), cp.end(),
[&](pair<int, int> x, pair<int, int> y) {
return x.se < y.se;
}
);
int tim = -1;
vector<int> rt(n), sz(n), dep(n, -1), par(n), tin(n);
vector<vector<int>> ch(n);
function<void(int, int)> dfs = [&](int x, int p) {
par[x] = p;
dep[x] = dep[p] + 1;
sz[x] = 1;
for (auto z : v[x]) {
if (z == p) continue;
dfs(z, x);
sz[x] += sz[z];
}
sort(v[x].begin(), v[x].end(),
[&](int x, int y) {
return sz[x] > sz[y];
}
);
};
dfs(0, -1);
function<void(int, int, int)> dfs2 = [&](int x, int p, int root) {
tin[x] = ++tim;
rt[x] = root;
ch[root].push_back(x);
bool ok = 1;
for (auto z : v[x]) {
if (z == p) continue;
if (ok) {
dfs2(z, x, root);
ok = 0;
} else {
dfs2(z, x, z);
}
}
};
dfs2(0, -1, 0);
vector<int> s(q), t(q), x(q), y(q);
vector<pair<int, int>> init(q), ans(q);
vector<vector<tuple<int, int, int>>> qr(m);
for (int i = 0; i < q; i++) {
cin >> s[i] >> t[i] >> x[i] >> y[i];
--s[i]; --t[i];
int lo = 0, hi = m - 1;
qr[(lo + hi) / 2].push_back({i, lo, hi});
}
for (int _ = 0; _ < 17; _++) {
vector<vector<tuple<int, int, int>>> tmp(m);
vector<pair<int, int>> val(n);
fenwick fw(n);
auto get = [&](int x, int y) {
pair<int, int> res = {0ll, 0ll};
while (rt[x] != rt[y]) {
if (dep[rt[x]] < dep[rt[y]]) swap(x, y);
res = fw.merge(res, fw.get(tin[rt[x]] + 1, tin[x]));
res = fw.merge(res, val[tin[rt[x]]]);
x = par[rt[x]];
}
if (dep[x] < dep[y]) swap(x, y);
res = fw.merge(res, fw.get(tin[y] + 1, tin[x]));
return res;
};
for (int i = 0; i < m; i++) {
auto [p, c] = cp[i];
int a_ = a[p], b_ = b[p];
if (dep[a_] < dep[b_]) swap(a_, b_);
fw.add(tin[a_], c);
val[tin[a_]].fi += c;
val[tin[a_]].se += 1;
for (auto [id, lo, hi] : qr[i]) {
auto res = get(s[id], t[id]);
if (res.fi <= y[id]) {
ans[id] = res;
lo = i + 1;
} else {
hi = i - 1;
}
tmp[(lo + hi) / 2].push_back({id, lo, hi});
}
}
if (_ == 0) {
for (int i = 0; i < q; i++) {
init[i] = get(s[i], t[i]);
}
}
swap(qr, tmp);
}
for (int i = 0; i < q; i++) {
ans[i].fi = max(-1ll, x[i] - (init[i].se - ans[i].se));
}
for (int i = 0; i < q; i++) {
cout << ans[i].fi << '\n';
}
return 0;
}
