#include <bits/stdc++.h>
using namespace std;
#define ff endl
#define lf "\n"
#define fi first
#define se second
#define _ << ' ' <<
#define all(x) begin(x),end(x)
#define rall(x) rbegin(x),rend(x)
#ifdef DEBUG
constexpr bool IS_DEBUG = 1;
#define infor(fmt, ...) do { print(stderr, fmt, ##__VA_ARGS__); } while(0)
#define infof(fmt, ...) do { println(stderr, fmt, ##__VA_ARGS__); } while(0)
#else
constexpr bool IS_DEBUG = 0;
#define infor(fmt, ...)
#define infof(fmt, ...)
#endif
using ll = long long;
using pll = pair<ll, ll>;
using pii = pair<int, int>;
template<typename... Args>
using vec = vector<Args...>;
mt19937 timmy_loves_gambling(73);
constexpr int LOG = 20;
constexpr int INF = 1e9;
struct Query {
int u, v;
int x;
ll y;
};
struct BIT {
struct Node {
Node(void): x(0), y(0) {}
int x;
ll y;
};
BIT(int N): N(N), T(N + 1) {}
void add(int i, int x, ll y) {
for(++i; i <= N; i += i&-i) {
T[i].x += x;
T[i].y += y;
}
}
void add(int l, int r, int x, ll y) {
add(l, x, y);
add(r, -x, -y);
}
Node query(int i) {
Node n;
for(++i; i > 0; i -= i&-i) {
n.x += T[i].x;
n.y += T[i].y;
}
return n;
}
int N;
vec<Node> T;
};
int main(void) {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int N, M, Q; cin >> N >> M >> Q;
vec<pii> ed(N - 1);
vec<vec<int>> adj(N);
for(auto &[u, v]: ed) {
cin >> u >> v;
u -= 1, v -= 1;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
}
vec<pll> E(M);
for(auto &[c, n]: E) {
cin >> n >> c;
n -= 1;
}
sort(rall(E));
vec<Query> Qs(Q);
for(auto &[u, v, x, y]: Qs) {
cin >> u >> v;
cin >> x >> y;
u -= 1, v -= 1;
}
vec<int> in(N), out(N);
vec<int> d(N), t_in(N), tour; tour.reserve(2 * N);
auto dfs = [&](int u, int f, auto &&dfs) -> void {
static int t = 0;
in[u] = t++;
t_in[u] = tour.size();
for(auto v: adj[u]) {
if(v == f) continue;
d[v] = 1 + d[u];
tour.emplace_back(u);
dfs(v, u, dfs);
}
out[u] = t;
tour.emplace_back(u);
};
dfs(0, -1, dfs);
const int T = tour.size();
vector tbl(LOG, vec<pii>(T));
for(int i = 0; i < T; ++i) {
tbl[0][i] = {d[tour[i]], tour[i]};
}
for(int lg = 0; lg < LOG - 1; ++lg) {
for(int i = 0; i + (1 << (lg+1)) < T; ++i) {
tbl[lg + 1][i] = min(tbl[lg][i], tbl[lg][i + (1 << lg)]);
}
}
auto get_lca = [&](int u, int v) -> int {
if(t_in[u] > t_in[v]) swap(u, v);
const int l = t_in[u], r = t_in[v] + 1;
const int lg = 31 - __builtin_clz(r - l);
return min(tbl[lg][l], tbl[lg][r - (1 << lg)]).se;
};
BIT bit(N);
int pos = 0;
for(auto &[c, n]: E) {
auto [u, v] = ed[n];
n = d[u] > d[v] ? u : v;
bit.add(in[n], out[n], 0, c);
}
vec<int> ans(Q, INF);
auto search = [&](int l, int r, vec<int> M, auto &&search) -> void {
int m = (l + r) / 2;
while(pos < m) {
auto [c, n] = E[pos++];
bit.add(in[n], out[n], 1, -c);
}
while(pos > m) {
auto [c, n] = E[--pos];
bit.add(in[n], out[n], -1, c);
}
vec<int> L, R;
for(auto q: M) {
auto [u, v, x, y] = Qs[q];
auto [x_u, y_u] = bit.query(in[u]);
auto [x_v, y_v] = bit.query(in[v]);
int lca = get_lca(u, v);
auto [x_lca, y_lca] = bit.query(in[lca]);
auto x_path = x_u + x_v - 2 * x_lca;
auto y_path = y_u + y_v - 2 * y_lca;
if(y >= y_path) {
ans[q] = min(ans[q], x_path);
}
if(r - l <= 1) continue;
(y >= y_path ? L : R).emplace_back(q);
}
if(L.size()) search(l, m, L, search);
if(R.size()) search(m, r, R, search);
};
vec<int> init(Q);
iota(all(init), 0);
search(0, M + 1, init, search);
for(int q = 0; q < Q; ++q) {
cout << (ans[q] > Qs[q].x ? -1 : Qs[q].x - ans[q]) << lf;
}
}
