#include <bits/stdc++.h>
#define ll long long
#define endl "\n"
#define fastIO cin.tie(nullptr); cout.tie(nullptr); ios::sync_with_stdio(false);
#define mid ((l + r) / 2)
#define lChild ((index * 2) + 1)
#define rChild ((index * 2) + 2)
/* ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣴⠶⠀⠀⠀⠀⠀⣈⣿⣦⠀⠀⠀⠀
⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⣴⣿⡿⠋⠀⠀⠀⠀⠀⠹⣿⣿⡆⠀⠀⠀
⠀ ⠀ ⠀⠀⠀⠀⠀⠀⢰⣿⣿⣤⣤⣴⣤⣤⣄⠀⢠⣿⣿⠇⠀⠀⠀
⠀ ⠀ ⠀⠀⠀⠀⠀⠀⢸⡿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡟⠀⠀⠀⠀
⠀⠀ ⠀ ⠀⠀⠀⠀⠀⣾⠋⠈⢻⣿⡝⠁⠀⢻⣿⣿⠋⠀⠀⠀⠀⠀
⠀⠀ ⠀ ⠀⠀⠀⠀⠈⣿⣄⣠⣿⣿⣧⣀⣠⣿⣿⣿⠀⠀⠀⠀⠀⠀
⠀⠀ ⠀ ⠀⠀⠀⠀⠀⢻⣿⣿⣿⣿⣿⣿⣿⣿⣿⡟⠀⠀⠀⠀⠀⠀
⠀ ⠀ ⠀⠀⠀⠀⠀⠀⠻⣿⣿⣿⣿⣿⣿⡿⠟⠀⣀⠀⠀⠀⠀⠀
⠀ ⠀⠀⠀⠀⠀⠀⠀⣰⣿⣿⣿⣿⣿⣿⣷⡾⠿⠛⠀⠀⠀⠀⠀
⠀ ⠀⠀⠀⠀⢀⣠⣴⣿⣿⣿⣿⣿⣿⣿⣿⡿⠓⠀⠀⠀⠀⠀⠀⠀
⠀⠀⢀⣴⣾⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣦⣀⡀⠀⠀⠀⠀⠀
⠀⣰⡟⠉⣼⣿⠟⣡⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣶⣤⡀⠀
⢠⣿⠀⠀⣿⣿⣾⠿⠛⣿⣿⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡛⠻⠑⡀
⠈⣿⠀⡼⢿⡏⠀⠀⠀⠹⣿⡆⠉⠻⣿⣿⣿⣿⣿⡻⢿⣿⠷⠞⠁
⠀⢸⠇⠀⠈⡇⠀⠀⠀⠀⠘⢿⡄⠀⠸⡏⠀⠀⠉⡇⠀⠹⢦⡄⠀
⠀ ⠀⠀⠀⠈⠁⠀⠀⠀⠀⠀⠸⠁⠀⠀⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀
No cost too great.
No mind to think.
No will to break.
*/
using namespace std;
ll t = 0;
vector<ll> euler;
struct node {
ll u, i;
};
void dfs(vector<vector<node> >& graph, vector<ll>& last, vector<ll>& depth, ll startIndex, ll p, ll d = 0) {
euler.push_back(startIndex);
depth[startIndex] = d;
last[startIndex] = euler.size() - 1;
for(auto [el, i] : graph[startIndex]) {
if(el == p) continue;
dfs(graph, last, depth, el, startIndex, d + 1);
euler.push_back(startIndex);
last[startIndex] = euler.size() - 1;
}
}
ll merge(ll lC, ll rC, vector<ll>& depth) {
if(lC == -1) return rC;
else if(rC == -1) return lC;
if(depth[lC] < depth[rC]) return lC;
else return rC;
}
ll build(vector<ll>& tree, vector<ll>& depth, ll l, ll r, ll index) {
if(l == r) return tree[index] = euler[l];
return tree[index] = merge( build(tree, depth, l, mid, lChild), build(tree, depth, mid + 1, r, rChild), depth);
}
ll query(vector<ll>& tree, vector<ll>& depth, ll l, ll r, ll qL, ll qR, ll index) {
if(r < qL || l > qR) return -1;
if(qL <= l && r <= qR) return tree[index];
return merge(query(tree, depth, l, mid, qL, qR, lChild), query(tree, depth, mid + 1, r, qL, qR, rChild), depth);
}
void pre(vector<vector<node> >& graph, vector<ll>& has, vector<ll>& edgeNum, ll curr, ll startIndex, ll p) {
edgeNum[startIndex] = curr;
for(auto [el, i] : graph[startIndex]) {
if(el == p) continue;
pre(graph, has, edgeNum, curr + has[i], el, startIndex);
}
}
void solve(ll _) {
ll n, m, q; cin>>n>>m>>q;
vector<vector<node> > graph(n);
for(int i = 0; i < n - 1; i++) {
ll x, y; cin>>x>>y;
x--; y--;
graph[x].push_back({y, i});
graph[y].push_back({x, i});
}
vector<ll> has(n, 0);
ll globalC;
for(int i = 0; i < m; i++) {
ll p, x; cin>>p>>x;
p--;
globalC = x;
has[p] += 1;
}
vector<ll> last(n, 0);
vector<ll> depth(n, 0);
dfs(graph, last, depth, 0, -1, 0);
vector<ll> tree(8 * n);
build(tree, depth, 0, euler.size() - 1, 0);
vector<ll> edgeNum(n, 0);
pre(graph, has, edgeNum, 0, 0, -1);
/* for(auto el : edgeNum) cout<<el<<" ";
cout<<endl;*/
for(int i = 0; i < q; i++) {
ll a, b, g, s; cin>>a>>b>>g>>s;
a--; b--;
if(last[a] > last[b]) swap(a, b);
ll lca = query(tree, depth, 0, euler.size() - 1, last[a], last[b], 0);
ll num = (edgeNum[a] + edgeNum[b] - (2 * edgeNum[lca]));
ll canRemove = (s / globalC) + g;
// cout<<a + 1<<", "<<b + 1<<" -> "<<num<<endl;
if(canRemove < num) cout<<-1<<endl;
else cout<<g - max(0ll, (num - (s / globalC)))<<endl;
}
}
int main() {
fastIO
//freopen("file.in", "r", stdin);
//freopen("file.out", "w", stdout);
ll t = 0; solve(t);
}
