#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define all(x) x.begin(), x.end()
#define pii pair<int, int>
const int N = 100087, mod = 998244353, M = N * 40, logN = 19;
vector <int> vec;
struct Seg {
static Seg mem[M], *pt;
int l, r, m, cnt;
ll sum;
Seg* ch[2];
Seg () = default;
Seg (int _l, int _r) : l(_l), r(_r), m(l + r >> 1), sum(0), cnt(0) {
if (r - l > 1) {
ch[0] = new (pt++) Seg(l, m);
ch[1] = new (pt++) Seg(m, r);
}
}
Seg (Seg *i) : l(i->l), r(i->r), m(i->m), sum(i->sum), cnt(i->cnt), ch{i->ch[0], i->ch[1]} {}
void pull() {sum = ch[0]->sum + ch[1]->sum, cnt = ch[0]->cnt + ch[1]->cnt;}
Seg* modify(int p) {
Seg *now = new (pt++) Seg(*this);
if (r - l == 1) {
now->sum += vec[l];
now->cnt += 1;
} else {
now->ch[p >= m] = ch[p >= m]->modify(p);
now->pull();
}
return now;
}
} Seg::mem[M], *Seg::pt = mem;
vector <pii> adj[N];
vector <int> cost[N];
int jump[N][logN], in[N], out[N], _t;
Seg* val[N];
void dfs(int v, int pa) {
in[v] = _t++, jump[v][0] = pa;
for (int j = 1; j < logN; ++j) {
int k = jump[v][j - 1];
jump[v][j] = ~k ? jump[k][j - 1] : -1;
}
for (auto [u, eid] : adj[v]) if (u != pa) {
val[u] = new (Seg::pt++) Seg(val[v]);
for (int w : cost[eid]) {
int id = lower_bound(all(vec), w) - vec.begin();
val[u] = val[u]->modify(id);
}
dfs(u, v);
}
out[v] = _t++;
}
int anc(int u, int v) {
return in[u] <= in[v] && out[u] >= out[v];
}
int lca(int u, int v) {
if (anc(u, v)) {
return u;
}
if (anc(v, u)) {
return v;
}
for (int i = logN - 1; ~i; --i) {
if (~jump[u][i] && !anc(jump[u][i], v)) {
u = jump[u][i];
}
}
return jump[u][0];
}
int query(int u, int v, ll tot) {
int l = lca(u, v);
Seg *tl = val[u], *tr = val[v], *tm = val[l];
int ans = 0;
while (tl->r - tl->l > 1) {
ll left = tl->ch[0]->sum + tr->ch[0]->sum - 2 * tm->ch[0]->sum;
if (left <= tot) {
tl = tl->ch[1];
tr = tr->ch[1];
tm = tm->ch[1];
tot -= left;
} else {
ans += tl->ch[1]->cnt + tr->ch[1]->cnt - 2 * tm->ch[1]->cnt;
tl = tl->ch[0];
tr = tr->ch[0];
tm = tm->ch[0];
}
}
int tmp = tl->cnt + tr->cnt - 2 * tm->cnt;
ans += tmp - min(tot / vec[tl->l], 1ll * tmp);
return ans;
}
int main() {
ios::sync_with_stdio(false), cin.tie(0);
int n, m, q;
cin >> n >> m >> q;
for (int i = 0, u, v; i < n - 1; ++i) {
cin >> u >> v, --u, --v;
adj[u].emplace_back(v, i);
adj[v].emplace_back(u, i);
}
for (int i = 0, u, v; i < m; ++i) {
cin >> u >> v, --u;
cost[u].pb(v);
vec.pb(v);
}
sort(all(vec)), vec.resize(unique(all(vec)) - vec.begin());
val[0] = new (Seg::pt++) Seg(0, int(vec.size()));
dfs(0, -1);
while (q--) {
int u, v, x; ll y;
cin >> u >> v >> x >> y, --u, --v;
int tmp = query(u, v, y);
cout << max(x - tmp, -1) << '\n';
}
}
/*
5 4 3
1 2
1 3
2 4
2 5
2 9
2 4
3 5
4 7
3 4 2 11
5 3 4 5
2 3 1 1
10 7 9
1 8
6 3
5 9
7 9
3 1
3 4
10 1
2 6
5 6
9 4
7 4
7 4
2 4
7 4
7 4
1 4
8 6 5 3
3 9 8 0
4 7 6 15
7 4 9 3
6 4 8 0
9 10 5 16
5 3 2 4
2 8 4 3
6 1 3 3
*/
