#include <bits/stdc++.h>
#define int long long
using namespace std;
const long long N = 1e6 + 5;
int a[N];
int n, m, q, u, v;
// const int N = 2e5 + 3;
vector<int> graph[N];
int st[N][22];
int cst[N][22];
int dist[N];
int mask;
int ans = 0;
void dfs(int node, int parent)
{
st[node][0] = parent;
dist[node] = dist[parent] + 1;
for (auto i : graph[node])
{
if (parent != i)
dfs(i, node);
}
}
void preprocess(int n)
{
for (int p = 1; p < 21; p++)
{
for (int i = 1; i <= n; i++)
{
// cout << i << " " << p << endl;
st[i][p] = st[st[i][p - 1]][p - 1];
cst[i][p] = cst[i][p - 1] + cst[st[i][p - 1]][p - 1];
}
}
}
void go_up(int &k, int binary)
{
for (int i = 0; i <= 20; i++)
{
mask = 1LL << i;
// cout << cst[6][0] << endl;
if ((binary & mask) != 0)
{
ans += cst[k][i];
k = st[k][i];
// cout << ans << endl;
}
}
}
int same_at_height(int u, int v)
{
if (u == v)
return v;
for (int i = 18; i >= 0; i--)
{
if (st[u][i] != st[v][i])
{
ans += cst[u][i] + cst[v][i];
u = st[u][i];
v = st[v][i];
}
}
ans += cst[u][0] + cst[v][0];
// cout << " at " << u << " " << v << endl;
// cout << ans << endl;
return st[u][0];
}
int lca(int u, int v)
{
if (dist[u] > dist[v])
swap(u, v);
int diff = dist[v] - dist[u];
// cout << " at " << v << " going up " << u << endl;
go_up(v, diff);
// cout << " at " << u << " " << v << endl;
// cout << ans << endl;
if (u == v)
return u;
return same_at_height(u, v);
}
void solve()
{
cin >> n >> m >> q;
vector<pair<int, int>> edges;
for (int i = 0; i < n - 1; i++)
{
cin >> u >> v;
graph[u].push_back(v);
graph[v].push_back(u);
edges.push_back({u, v});
}
dfs(1, 0);
int cost;
// for (int i = 0; i < n; i++)
// {
// cout << st[i][0] << " ";
// }
// cout << endl;
for (int i = 0; i < m; i++)
{
int p, c;
cin >> p >> c;
p--;
if (dist[edges[p].first] > dist[edges[p].second])
{
cst[edges[p].first][0] += 1;
// cout << edges[p].first << " " << cst[edges[p].first][0];
}
else
{
cst[edges[p].second][0] += 1;
// cout << edges[p].second << " " << cst[edges[p].second][0] << endl;
}
// cout << endl;
cost = c;
}
// cout << "done" << endl;
// for (int i = 0; i < n; i++)
// {
// cout << cst[i][0] << " ";
// }
preprocess(n + 1);
// cout << endl;
// for (int i = 0; i < n; i++)
// {
// cout << st[i][0] << " ";
// }
// cout << endl;
// cout << st[8][0] << endl;
// cout << cst[9][2] << endl;
int starting, ending, silver, gold;
for (int i = 0; i < q; i++)
{
cin >> starting >> ending >> gold >> silver;
ans = 0;
lca(starting, ending);
int can_buy = silver / cost;
// use gold for the remiaining
int gold_buy = max(0ll, ans - can_buy);
// cout << ans << endl;
gold_buy = min(gold_buy, gold);
if (can_buy + gold_buy < ans)
cout << -1 << endl;
else
cout << gold - gold_buy << endl;
}
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
int t = 1;
// cin >> t;
for (int i = 1; i <= t; i++)
{
// cout << "Case #" << i << ':' << ' ';
solve();
cout << endl;
}
return 0;
}
