#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define st first
#define nd second
#define pb push_back
const int MAXN = 1 << 17;
const int MAXK = 20;
int n, m, q;
int skok[MAXN][MAXK];
int depth[MAXN];
int pot[MAXK];
ll pom[MAXN];
bool czy[MAXN];
vector<pair<int, ll>> jakie[MAXN];
ll liczba[MAXN];
ll ile[MAXN];
int policz[MAXN];
int ans[MAXN];
int lastans[MAXN];
int preorder[MAXN];
int postorder[MAXN];
vector<int> graf[MAXN];
pair<ll, ll> monety[MAXN];
vector<pair<pair<int, int>, ll>> vec;
int kt = 1;
int kt2 = 1;
int uz = 0;
struct trojka {
int a, b, c;
};
trojka pyt[MAXN];
void dfs(int v, int last) {
preorder[v] = kt;
kt++;
depth[v] = depth[last] + 1;
skok[v][0] = last;
for (int k = 1; k < MAXK; k++) {
skok[v][k] = skok[skok[v][k - 1]][k - 1];
}
for (auto w: graf[v]) {
if (w == last) continue;
dfs(w, v);
}
postorder[v] = kt2;
kt2++;
}
int lca(int a, int b) {
if (depth[a] > depth[b]) {
swap(a, b);
}
int k = MAXK - 1;
while (depth[a] != depth[b]) {
if ((depth[b] - pot[k]) >= depth[a]) {
b = skok[b][k];
}
k--;
}
if (a == b) {
return a;
}
k = MAXK - 1;
while (skok[a][0] != skok[b][0]) {
if (skok[a][k] != skok[b][k]) {
a = skok[a][k];
b = skok[b][k];
}
k--;
}
return skok[a][0];
}
void dfs2(int v, int last, ll val, int val2) {
val += pom[v];
val2 += policz[v];
// cout << "v = " << v << '\n';
for (auto p: jakie[v]) {
// cout << "nr = " << p.st << " ile = " << p.nd << '\n';
ile[p.st] += (val * p.nd);
ans[p.st] += (val2 * p.nd);
}
for (auto syn: graf[v]) {
if (syn == last) continue;
dfs2(syn, v, val, val2);
}
}
bool czyojc(int a, int b) {
if (preorder[a] <= preorder[b] && postorder[a] >= postorder[b]) {
return true;
}
return false;
}
void zrob() {
dfs2(1, 1, 0ll, 0);
rep(i, q) {
if (czy[i]) continue;
// cout << "liczba = " << liczba[i] << " ile = " << ile[i] << '\n';
if (ile[i] >= liczba[i]) {
// cout << "i = " << i << endl;
czy[i] = true;
int it = 0;
int t = 0;
while (liczba[i] > 0) {
int x = vec[it].st.st;
int y = vec[it].st.nd;
ll lic = vec[it].nd;
// cout << "x = " << x << " y = " << y << " lic = " << lic << '\n';
if (czyojc(pyt[i].c, x) && (czyojc(y, pyt[i].a) || czyojc(y, pyt[i].b))) {
// cout << "TAK" << endl;
t++;
liczba[i] -= lic;
}
it++;
}
if (liczba[i] < 0) {
t--;
}
// cout << "i = " << i << " t = " << t << '\n';
ans[i] -= (lastans[i] + t);
}
else {
liczba[i] -= ile[i];
}
}
rep(i, q) {
lastans[i] = ans[i];
ile[i] = 0;
}
rep(i, n + 1) {
pom[i] = 0;
policz[i] = 0;
}
vec.clear();
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
pot[0] = 1;
for (int k = 1; k < MAXK; k++) {
pot[k] = pot[k - 1] * 2;
}
cin >> n >> m >> q;
vector<pair<int, int>> kraw;
int sqr = 330;
rep(i, n - 1) {
int a, b;
cin >> a >> b;
graf[a].pb(b);
graf[b].pb(a);
kraw.pb({a, b});
}
dfs(1, 1);
vector<pair<ll, int>> checks;
rep(i, m) {
int p;
ll c;
cin >> p >> c;
p--;
checks.pb({c, p});
}
rep(i, q) {
int a, b;
ll x, y;
cin >> a >> b >> x >> y;
monety[i] = {x, y};
liczba[i] = y;
int c = lca(a, b);
pyt[i] = {a, b, c};
jakie[a].pb({i, 1});
jakie[b].pb({i, 1});
jakie[c].pb({i, -2});
}
sort(checks.begin(), checks.end());
for (auto p: checks) {
int x = kraw[p.nd].st;
int y = kraw[p.nd].nd;
if (czyojc(y, x)) {
swap(x, y);
}
vec.pb({{x, y}, p.st});
policz[y]++;
pom[y] += p.st;
int sz = vec.size();
if (sz >= sqr) {
zrob();
}
}
zrob();
rep(i, q) {
if (!czy[i]) {
ans[i] = 0;
}
ll odp = monety[i].st - (long long)ans[i];
if (odp < 0) {
cout << -1 << '\n';
}
else {
cout << odp << '\n';
}
}
return 0;
}
