#include <bits/stdc++.h>
using namespace std;
#define POPCOUNT(n) (__builtin_popcountll((n)))
#define CLZ(n) (__builtin_clzll((n)))
#define CTZ(n) (__builtin_ctzll((n)))
#define LOG(n) (63 - __builtin_clzll((n)))
#define BIT(n, i) (((n) >> (i)) & 1ll)
#define MASK(i) (1ll << (i))
#define FLIP(n, i) ((n) ^ (1ll << (i)))
#define ON(n, i) ((n) | MASK(i))
#define OFF(n, i) ((n) & ~MASK(i))
#define Int __int128
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long long, int> pli;
typedef pair<int, long long> pil;
typedef vector<pair<int, int>> vii;
typedef vector<pair<long long, long long>> vll;
typedef vector<pair<long long, int>> vli;
typedef vector<pair<int, long long>> vil;
template <class T1, class T2> bool maximize(T1 &x, T2 y) {
if (x < y) {
x = y;
return true;
}
return false;
}
template <class T1, class T2> bool minimize(T1 &x, T2 y) {
if (x > y) {
x = y;
return true;
}
return false;
}
template <class T> void remove_duplicate(vector<T> &ve) {
sort (ve.begin(), ve.end());
ve.resize(unique(ve.begin(), ve.end()) - ve.begin());
}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
long long random(long long l, long long r) {
return uniform_int_distribution<long long>(l, r)(rng);
}
unsigned long long random(unsigned long long l, unsigned long long r) {
return uniform_int_distribution<unsigned long long>(l, r)(rng);
}
template <class T> T random(T r) {
return rng() % r;
}
const int N = 1e5 + 5, LG = 18;
const int MOD = 1e9 + 7;
const int inf = 1e9;
const long long INF = 1e18;
int n, m, q, dfsTime = 0;
int ver[N], dep[N], up[N][LG];
int tin[N], tout[N], low[N], high[N], ans[N];
pii edges[N], checkpoints[N];
vii adj[N];
struct Query {
int s, t, x; ll y;
Query(int _s = 0, int _t = 0, int _x = 0, ll _y = 0) {
s = _s, t = _t, x = _x, y = _y;
}
} que[N];
void dfs(int u, int fa) {
tin[u] = ++dfsTime;
for (auto [v, id] : adj[u]) if (v != fa) {
ver[id] = v, dep[v] = dep[u] + 1, up[v][0] = u;
for (int i = 1; i < LG; ++i) up[v][i] = up[up[v][i - 1]][i - 1];
dfs(v, u);
}
tout[u] = dfsTime;
}
int lca(int u, int v) {
if (dep[u] < dep[v]) swap(u, v);
int delta = dep[u] - dep[v];
for (int i = 0; MASK(i) <= delta; ++i)
if (BIT(delta, i)) u = up[u][i];
if (u == v) return u;
for (int i = LOG(dep[u]); i >= 0; --i)
if (up[u][i] != up[v][i]) {
u = up[u][i], v = up[v][i];
}
return up[u][0];
}
struct FenwickTree {
using T = long long;
vector<T> bit;
FenwickTree() {}
void resize(int n) {
bit.assign(n + 1, 0);
}
void update(int p, T val) {
for (; p < int(bit.size()); p += p & -p) bit[p] += val;
}
void update(int l, int r, T val) {
update(l, val), update(r + 1, -val);
}
T get(int p) {
T ans = 0;
for (; p > 0; p -= p & -p) ans += bit[p];
return ans;
}
} fen_sum, fen_cnt;
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n >> m >> q;
for (int i = 1; i < n; ++i) {
int u, v; cin >> u >> v;
adj[u].emplace_back(v, i);
adj[v].emplace_back(u, i);
edges[i] = make_pair(u, v);
}
dfs(1, -1);
for (int i = 1; i < n; ++i) {
auto &[u, v] = edges[i];
if (u == ver[i]) swap(u, v);
// cerr << u << ' ' << v << '\n';
}
// cerr << '\n';
for (int i = 1; i <= m; ++i) {
int p, c; cin >> p >> c;
checkpoints[i] = make_pair(c, p);
}
sort (checkpoints + 1, checkpoints + 1 + m);
for (int i = 1; i <= q; ++i) {
int s, t, x; ll y; cin >> s >> t >> x >> y;
que[i] = Query(s, t, x, y);
low[i] = 1, high[i] = inf, ans[i] = 0;
}
while (true) {
vii ve;
for (int i = 1; i <= q; ++i) if (low[i] <= high[i]) {
int mid = (low[i] + high[i]) >> 1;
ve.emplace_back(mid, i);
}
if (ve.empty()) break;
sort (ve.begin(), ve.end());
int j = 0; fen_sum.resize(n), fen_cnt.resize(n);
for (auto [mid, id] : ve) {
while (j < m && checkpoints[j + 1].fi <= mid) {
int v = edges[checkpoints[++j].se].se;
fen_sum.update(tin[v], tout[v], checkpoints[j].fi);
fen_cnt.update(tin[v], tout[v], 1);
}
auto [s, t, _, y] = que[id]; int p = lca(s, t);
ll sum = fen_sum.get(tin[s]) + fen_sum.get(tin[t]) - 2 * fen_sum.get(tin[p]);
int cnt = fen_cnt.get(tin[s]) + fen_cnt.get(tin[t]) - 2 * fen_cnt.get(tin[p]);
if (sum >= y) {
// cerr << "mid " << mid << ' ' << id << ' ' << sum << ' ' << cnt << ' ' << (sum - y + mid - 1) / mid << '\n';
high[id] = mid - 1;
ans[id] = cnt - (sum - y + mid - 1) / mid;
}
else low[id] = mid + 1;
}
}
for (int i = 1; i <= q; ++i) {
auto [s, t, x, _] = que[i];
int gold = (dep[s] + dep[t] - 2 * dep[lca(s, t)]) - ans[i];
// cerr << gold << '\n';
if (gold <= que[i].x) cout << que[i].x - gold << '\n';
else cout << "-1\n";
}
return 0;
}
