#include <bits/stdc++.h>
using namespace std;
typedef int64_t ll;
#define all(x) x.begin(), x.end()
//#define size(x) (int)x.size()
template<class S, class T>
bool chmin(S &a, const T &b) {
return (a > b ? (a = b) == b : false);
}
template<class S, class T>
bool chmax(S &a, const T &b) {
return (a < b ? (a = b) == b : false);
}
const int inf = 1e9;
const ll INF = 1e18;
const int mod = 998244353;
const int N = 1e5 + 1;
int C;
signed main() {
cin.tie(nullptr)->sync_with_stdio(false);
int n, m, q;
cin >> n >> m >> q;
int a[n], b[n];
vector<int> c[n], g[n + 1];
map<pair<int, int>, int> ind;
for (int i = 1; i < n; ++i) {
cin >> a[i] >> b[i];
g[a[i]].push_back(b[i]);
g[b[i]].push_back(a[i]);
ind[{a[i], b[i]}] = i;
ind[{b[i], a[i]}] = i;
}
for (int i = 0; i < m; ++i) {
int j, w;
cin >> j >> w;
C = w;
c[j].push_back(w);
}
if (n <= 2000 && m <= 2000 && q <= 2000) {
vector<int> p(n + 1, 0);
function<void(int, int)> dfs = [&](int v, int parent) {
for (int to : g[v]) {
if (to != parent) {
p[to] = v;
dfs(to, v);
}
}
};
while (q--) {
int a, b, x; ll y;
cin >> a >> b >> x >> y;
vector<int> path;
dfs(a, 0);
int v = b;
while (v) {
path.push_back(v);
v = p[v];
}
vector<int> cost;
for (int i = 0; i + 1 < (int)path.size(); ++i) {
for (int j : c[ind[{path[i], path[i + 1]}]]) {
cost.push_back(j);
}
}
sort(all(cost), greater<int>());
while (!cost.empty() && y - cost.back() >= 0) {
y -= cost.back();
cost.pop_back();
}
x -= size(cost);
cout << (x < 0 ? -1 : x) << '\n';
for (int i = 1; i <= n; ++i) {
p[i] = 0;
}
}
} else {
vector<int> tin(n + 1), tout(n + 1), val(n + 1, 0);
vector<vector<int>> up(n + 1, vector<int> (17, 1));
int timer = -1;
function<void(int, int)> dfs = [&](int v, int p) {
val[v] += (int)c[ind[{v, p}]].size();
tin[v] = ++timer;
up[v][0] = p;
for (int i = 1; i < 17; ++i) {
up[v][i] = up[up[v][i - 1]][i - 1];
}
for (int to : g[v]) {
if (to != p) {
val[to] += val[v];
dfs(to, v);
}
}
tout[v] = ++timer;
};
auto upper = [&](int u, int v) {
return tin[u] <= tin[v] && tout[u] >= tout[v];
};
auto get_lca = [&](int u, int v) {
if (upper(u, v)) return u;
if (upper(v, u)) return v;
for (int i = 16; i >= 0; --i) {
if (!upper(up[u][i], v)) {
u = up[u][i];
}
}
return up[u][0];
};
dfs(1, 1);
while (q--) {
int a, b, x; ll y;
cin >> a >> b >> x >> y;
if (upper(a, b)) {
int need = val[b] - val[a];
y /= C;
if (need <= y) {
cout << x << '\n';
} else {
need -= y;
x -= need;
cout << (x < 0 ? -1 : x) << '\n';
}
} else if (upper(b, a)) {
swap(a, b);
int need = val[b] - val[a];
y /= C;
if (need <= y) {
cout << x << '\n';
} else {
need -= y;
x -= need;
cout << (x < 0 ? -1 : x) << '\n';
}
} else {
int lca = get_lca(a, b);
int need = val[b] + val[a] - val[lca] * 2;
y /= C;
if (need <= y) {
cout << x << '\n';
} else {
need -= y;
x -= need;
cout << (x < 0 ? -1 : x) << '\n';
}
}
}
}
}
