/*
Podzadanie: wszystkie c_i równe
Zliczamy, ile jest bramek na ścieżce drzewem przedziałowym jak we wzorcówce.
*/
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define st first
#define nd second
typedef long long ll;
typedef long double ld;
const int II = 1'000'000'000;
const ll I = 1'000'000'000'000'000'000LL;
const int K = 17;
const int N = 1 << K;
pair<int, int> e[N];
vector<int> ed[N];
int jp[N][K + 1];
int pos[N], pre[N], cnt = 0;
ll drz[2 * N];
pair<ll, ll> il[N];
int v1[N], v2[N], l[N];
int poc[N], kon[N];
ll akt[N];
pair<int, int> que[N];
pair<int, int> dod[N];
ll answer[N];
void Add(int a, int b, ll x)
{
a += N - 1;
b += N + 1;
while (a / 2 != b / 2)
{
if (a % 2 == 0)
drz[a + 1] += x;
if (b % 2 == 1)
drz[b - 1] += x;
a /= 2;
b /= 2;
}
}
ll Sum(int v)
{
ll ans = 0LL;
v += N;
while (v > 0)
{
ans += drz[v];
v /= 2;
}
return ans;
}
void DFS(int v)
{
++cnt;
pre[v] = cnt;
pos[v] = cnt;
for (int i = 1; i <= K; ++i)
jp[v][i] = jp[jp[v][i - 1]][i - 1];
for (int i = 0; i < (int)ed[v].size(); ++i)
{
if (pre[ed[v][i]])
continue;
jp[ed[v][i]][0] = v;
DFS(ed[v][i]);
pos[v] = pos[ed[v][i]];
}
}
int LCA(int a, int b)
{
if (pre[a] > pre[b])
swap(a, b);
for (int i = K; i >= 0; --i)
if (pos[jp[a][i]] < pre[b])
a = jp[a][i];
if (pos[a] < pre[b])
a = jp[a][0];
return a;
}
void Solve()
{
int n, m, q, a, b;
ll cost;
cin >> n >> m >> q;
for (int i = 1; i < n; ++i)
{
cin >> a >> b;
e[i] = pair{a, b};
ed[a].pb(b);
ed[b].pb(a);
}
jp[1][0] = 1;
DFS(1);
for (int i = 1; i <= m; ++i)
{
cin >> a >> cost;
if (jp[e[a].st][0] == e[a].nd)
a = e[a].st;
else
a = e[a].nd;
Add(pre[a],pos[a],1);
}
for (int i = 1; i <= q; ++i)
{
cin >> v1[i] >> v2[i] >> il[i].st >> il[i].nd;
l[i] = LCA(v1[i], v2[i]);
ll gates = max(0ll, Sum(pre[v1[i]]) + Sum(pre[v2[i]]) - 2*Sum(pre[l[i]]) - il[i].nd/cost);
if (gates > il[i].st)cout << "-1\n";
else cout << il[i].st - gates << '\n';
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
Solve();
return 0;
}
