#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef pair<int,int> pii;
const int M = 1e5 + 6;
int n, m, q;
vector<int> g[M];
pii e[M];
int cost[M], in[M], out[M];
int anc[M][18], depth[M];
int d[M], ini[M], Lca[M];
int timedfs = 0;
ll L[M], R[M], MID[M], ans[M];
struct query {
int s, t;
ll x, y;
} Q[M];
struct Fenwick {
ll f[M];
int n;
void resize(int x) { n = x; fill(f, f + n + 1, 0); }
void update(int i, int val) {
for (; i <= n; i += i & -i) f[i] += val;
}
ll GET(int i) {
ll res = 0;
for (; i > 0; i -= i & -i) res += f[i];
return res;
}
} BIT, CNT;
void dfs(int u, int p) {
in[u] = ++timedfs;
anc[u][0] = p;
for (int v : g[u]) {
if (v == p) continue;
depth[v] = depth[u] + 1;
dfs(v, u);
}
out[u] = timedfs;
}
int get_lca(int u, int v) {
if (depth[u] < depth[v]) swap(u, v);
for (int k = 17; k >= 0; k--)
if (depth[u] - (1 << k) >= depth[v]) u = anc[u][k];
if (u == v) return u;
for (int k = 17; k >= 0; k--)
if (anc[u][k] != anc[v][k]) {
u = anc[u][k];
v = anc[v][k];
}
return anc[u][0];
}
void prework(int u, int p) {
for (int v : g[u]) {
if (v == p) continue;
d[v] += d[u];
prework(v, u);
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
if (!(cin >> n >> m >> q)) return 0;
for (int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
g[u].pb(v); g[v].pb(u);
e[i] = {u, v};
}
memset(cost, -1, sizeof(cost));
for (int i = 1; i <= m; i++) {
int p, c; cin >> p >> c;
cost[p] = c;
}
dfs(1, 0);
for (int k = 1; k < 18; k++)
for (int i = 1; i <= n; i++)
anc[i][k] = anc[anc[i][k-1]][k-1];
// Đảm bảo e[i].se luôn là nút con
for (int i = 1; i < n; i++)
if (depth[e[i].fi] > depth[e[i].se]) swap(e[i].fi, e[i].se);
vector<int> id;
for (int i = 1; i < n; i++) {
if (cost[i] != -1) {
id.pb(i);
d[e[i].se] = 1; // Đánh dấu cạnh có thể sử dụng
}
}
sort(all(id), [](int a, int b) { return cost[a] < cost[b]; });
prework(1, 0);
for (int i = 1; i <= q; i++) {
cin >> Q[i].s >> Q[i].t >> Q[i].x >> Q[i].y;
Lca[i] = get_lca(Q[i].s, Q[i].t);
ini[i] = d[Q[i].s] + d[Q[i].t] - 2 * d[Lca[i]];
L[i] = 0; R[i] = 1e9;
ans[i] = Q[i].x - ini[i]; // Mặc định là x trừ đi tổng số cạnh có giá (chưa khôi phục cái nào)
}
while (true) {
vector<int> queries;
for (int i = 1; i <= q; i++) if (L[i] <= R[i]) queries.pb(i);
if (queries.empty()) break;
sort(all(queries), [](int a, int b) { return (L[a] + R[a]) / 2 < (L[b] + R[b]) / 2; });
BIT.resize(n);
CNT.resize(n);
int pt = 0;
for (int i : queries) {
ll mid = (L[i] + R[i]) / 2;
while (pt < id.size() && cost[id[pt]] <= mid) {
int v = e[id[pt]].se;
BIT.update(in[v], cost[id[pt]]);
BIT.update(out[v] + 1, -cost[id[pt]]);
CNT.update(in[v], 1);
CNT.update(out[v] + 1, -1);
pt++;
}
ll current_cost = BIT.GET(in[Q[i].s]) + BIT.GET(in[Q[i].t]) - 2 * BIT.GET(in[Lca[i]]);
ll count_edges = CNT.GET(in[Q[i].s]) + CNT.GET(in[Q[i].t]) - 2 * CNT.GET(in[Lca[i]]);
if (current_cost <= Q[i].y) {
ans[i] = Q[i].x - ini[i] + count_edges;
L[i] = mid + 1;
} else {
R[i] = mid - 1;
}
}
}
for (int i = 1; i <= q; i++) {
cout << (ans[i] < 0 ? -1 : ans[i]) << endl;
}
return 0;
}
