#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define int long long
using namespace std;
struct node {
int s, t, x, y;
};
const int N = 2e5 + 2;
const int L = 20;
int dp[L][N];
int tin[N];
int sz[N];
int H[N];
int up[N];
pair<int, int> t[5 * N];
vector<int> g[N];
void dfs1(int u, int p) {
sz[u] = 1;
H[u] = H[p] + 1;
dp[0][u] = p;
for (int i = 1; i < L; i++) {
dp[i][u] = dp[i - 1][dp[i - 1][u]];
}
for (auto v: g[u]) {
if (v == p) continue;
dfs1(v, u);
sz[u] += sz[v];
}
}
int time_now = 0;
void dfs2(int u, int p) {
tin[u] = time_now++;
for (int i = 1; i < g[u].size(); i++) {
if (g[u][i] == p) continue;
if (sz[g[u][i]] > sz[g[u][0]] or g[u][0] == p) swap(g[u][i], g[u][0]);
}
for (int i = 0; i < g[u].size(); i++) {
if (g[u][i] == p) continue;
if (i == 0)up[g[u][i]] = up[u];
else up[g[u][i]] = g[u][i];
dfs2(g[u][i], u);
}
}
int LA(int u, int h) {
for (int i = 0; i < L; i++) {
if ((1 << i) & h) {
h -= (1 << i);
u = dp[i][u];
}
}
return u;
}
int LCA(int u, int v) {
int h1 = H[u], h2 = H[v];
if (h1 > h2) {
u = LA(u, h1 - h2);
}
if (h2 > h1) {
v = LA(v, h2 - h1);
}
for (int i = L - 1; i > -1; i--) {
if (dp[i][u] != dp[i][v]) {
u = dp[i][u];
v = dp[i][v];
}
}
if (u == v) return u;
return dp[0][u];
}
void upd(int ind, int l, int r, int id, pair<int, int> x) {
if (l + 1 == r) {
t[ind].first += x.first;
t[ind].second += x.second;
return;
}
int mid = (l + r) / 2;
if (mid > id) {
upd(ind * 2, l, mid, id, x);
} else {
upd(ind * 2 + 1, mid, r, id, x);
}
t[ind].first += x.first;
t[ind].second += x.second;
}
pair<int, int> get(int ind, int l, int r, int ql, int qr) {
if (l >= ql and r <= qr) {
return t[ind];
}
if (l >= qr or r <= ql) {
return {0, 0};
}
int mid = (l + r) / 2;
pair<int, int> ans1 = get(ind * 2, l, mid, ql, qr);
pair<int, int> ans2 = get(ind * 2 + 1, mid, r, ql, qr);
return {ans1.first + ans2.first, ans1.second + ans2.second};
}
pair<int, int> bup(int u, int lca, int h) {
int sm = 0, cnt = 0;
while (H[up[u]] > H[lca]) {
pair<int, int> o = get(1, 0, 1 << h, tin[up[u]], tin[u] + 1);
sm += o.first, cnt += o.second;
u = dp[0][up[u]];
}
pair<int, int> o = get(1, 0, 1 << h, tin[lca] + 1, tin[u] + 1);
sm += o.first, cnt += o.second;
return {sm, cnt};
}
int gt(int u, int v, int y, int h, int ans) {
int lca = LCA(u, v);
int sms = 0, cnts = 0;
pair<int, int> o1 = bup(u, lca, h), o2 = bup(v, lca, h);
sms = o1.first + o2.first;
cnts += o1.second + o2.second;
if (sms > y) return 1e9;
return max(ans - cnts, 0LL);
}
signed main() {
cin.tie(nullptr)->sync_with_stdio(false);
int n, m, q;
cin >> n >> m >> q;
vector<pair<int, int>> pr;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
u--, v--;
g[u].push_back(v);
g[v].push_back(u);
pr.push_back({u, v});
}
vector<pair<int, int>> cst;
for (int i = 0; i < m; i++) {
int p, c;
cin >> p >> c;
p--;
cst.push_back({p, c});
}
dfs1(0, 0);
dfs2(0, 0);
int h = 0;
while (1 << (++h) <= time_now);
vector<pair<int, int>> n_c;
for (auto [id, c]: cst) {
int u = pr[id].first, v = pr[id].second;
if (tin[v] < tin[u]) swap(u, v);
n_c.push_back({c, v});
}
vector<node> qus(q);
for (int i = 0; i < q; i++) {
int start, fin, x, y;
cin >> start >> fin >> x >> y;
start--, fin--;
node nd;
nd.s = start, nd.t = fin, nd.x = x, nd.y = y;
qus[i] = nd;
}
n_c.push_back({-1e9, -1e9});
std::sort(n_c.begin(), n_c.end());
vector<pair<int, int>> bin_pow(q, {0, n_c.size()});
vector<int> ans(q, 1e9);
vector<vector<int>> upds(n_c.size());
vector<int> szs(q);
for (int i = 0; i < n_c.size(); i++) {
if (i != 0)upd(1, 0, 1 << h, tin[n_c[i].second], {n_c[i].first, 1});
}
for (int i = 0; i < q; i++) {
int u = qus[i].s, v = qus[i].t;
int lca = LCA(u, v);
szs[i] += bup(u, lca, h).second + bup(v, lca, h).second;
ans[i] = szs[i];
}
for (int i = 0; i < n_c.size(); i++) {
if (i != 0)upd(1, 0, 1 << h, tin[n_c[i].second], {-n_c[i].first, -1});
}
while (true) {
bool check = false;
upds.clear();
upds.resize(n_c.size());
for (int i = 0; i < q; i++) {
if (bin_pow[i].first + 1 == bin_pow[i].second) continue;
check = true;
upds[(bin_pow[i].first + bin_pow[i].second) / 2].push_back(i);
}
if (!check) break;
for (int i = 0; i < n_c.size(); i++) {
if (i != 0) upd(1, 0, 1 << h, tin[n_c[i].second], {n_c[i].first, 1});
for (auto ind: upds[i]) {
int an = gt(qus[ind].s, qus[ind].t, qus[ind].y, h, szs[ind]);
ans[ind] = min(ans[ind], an);
if (an != 1e9) {
bin_pow[ind].first = i;
} else {
bin_pow[ind].second = i;
}
}
}
for (int i = 0; i < n_c.size(); i++) {
if (i != 0)upd(1, 0, 1 << h, tin[n_c[i].second], {-n_c[i].first, -1});
}
}
for (int i = 0; i < q; i++) {
cout << max(-1LL, qus[i].x - ans[i]) << '\n';
}
}
