#include "bits/stdc++.h"
using namespace std;
#define task ""
#define ll long long
#define endl '\n'
#define fi first
#define se second
#define vall(a) (a).begin(), (a).end()
#define sze(a) (int)a.size()
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ep emplace_back
#define pb push_back
#define pf push_front
const ll mod = 1e9 + 7;
const int N = 2e5 + 5;
const ll oo = 1e18;
bool START;
int n, q, m;
pii s[N << 1][20];
int T[N], st[N], en[N], rd[N], h[N];
vector<pii> adj[N];
int cur = 0, t = 0;
void dfs(int u, int p) {
T[u] = ++cur;
st[u] = ++t;
s[cur][0] = make_pair(h[u], u);
for (auto[v, id] : adj[u]) {
if (v == p) continue;
rd[id] = v;
h[v] = h[u] + 1;
dfs(v, u);
s[++cur][0] = make_pair(h[u], u);
}
en[u] = ++t;
}
int lg[N << 1];
void build() {
dfs(1, 0);
for (int i = 2; i <= cur; ++i) lg[i] = lg[i >> 1] + 1;
for (int i = 1; (1 << i) <= cur; ++i) {
for (int j = 1; j + (1 << i) - 1 <= cur; ++j) s[j][i] = min(s[j][i - 1], s[j + (1 << (i - 1))][i - 1]);
}
}
int lca(int u, int v) {
if (T[u] < T[v]) swap(u, v);
int k = lg[T[u] - T[v] + 1];
return min(s[T[u] - (1 << k) + 1][k], s[T[v]][k]).se;
}
struct queries {
int u, v, x;
ll y;
int id;
queries(int u_, int v_, int x_, ll y_, int id_) : u(u_), v(v_), x(x_), y(y_), id(id_) {}
};
vector<queries> Q;
struct BIT {
ll bit[N << 1];
void add(int idx, ll delta) {
for (; idx <= t; idx += idx & -idx) bit[idx] += delta;
}
ll get(int idx) {
ll ans = 0;
for (; idx > 0; idx -= idx & -idx) ans += bit[idx];
return ans;
}
ll get(int l, int r) {
return get(r) - get(l - 1);
}
} bit;
ll get(int u, int v) {
int lck = lca(u, v);
return bit.get(st[u]) + bit.get(st[v]) - (bit.get(st[lck]) << 1);
}
vector<queries> pos[N];
pair<int, ll> e[N];
void dnc(int l, int r, vector<queries> curq) {
if (l == r) {
for (queries qq : curq) pos[l].pb(qq);
return;
}
int mid = (l + r) >> 1;
for (int i = mid; i >= l; --i) {
bit.add(st[rd[e[i].fi]], e[i].se);
bit.add(en[rd[e[i].fi]], -e[i].se);
}
vector<queries> ql, qr;
for (auto[u, v, x, y, id] : curq) {
ll cost = get(u, v);
if (cost > y) {
ql.pb(queries(u, v, x, y, id));
} else {
qr.pb(queries(u, v, x, y - cost, id));
}
}
for (int i = mid; i >= l; --i) {
bit.add(st[rd[e[i].fi]], -e[i].se);
bit.add(en[rd[e[i].fi]], e[i].se);
}
curq.clear();
dnc(l, mid, ql);
dnc(mid + 1, r, qr);
}
bool cmp(pii x, pii y) {
return x.se < y.se;
}
int ans[N];
inline void solve() {
build();
sort(e + 1, e + 1 + m, cmp);
dnc(1, m + 1, Q);
memset(bit.bit, 0, sizeof(bit.bit));
for (int i = 1; i <= q; ++i) ans[i] = -1;
for (auto[u, v, x, y, id] : pos[m + 1]) if (get(u, v) <= x) ans[id] = x - get(u, v);
for (int i = m; i >= 1; --i) {
bit.add(st[rd[e[i].fi]], 1);
bit.add(en[rd[e[i].fi]], -1);
for (auto[u, v, x, y, id] : pos[i]) if (get(u, v) <= x) ans[id] = x - get(u, v);
}
for (int i = 1; i <= q; ++i) cout << ans[i] << endl;
}
inline void input() {
cin >> n >> m >> q;
for (int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
adj[u].pb(make_pair(v, i));
adj[v].pb(make_pair(u, i));
}
for (int i = 1; i <= m; ++i) cin >> e[i].fi >> e[i].se;
for (int i = 1; i <= q; ++i) {
int u, v, x;
ll y;
cin >> u >> v >> x >> y;
Q.pb(queries(u, v, x, y, i));
}
return solve();
}
bool END;
int main() {
if(fopen(task ".inp", "r")) {
freopen(task ".inp", "r", stdin);
freopen(task ".out", "w", stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
input();
cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << 's' << endl;
cerr << "Memory: " << fabs ((&END - &START)) / 1048576.0 << "MB\n";
return 0;
}
