#include <bits/stdc++.h>
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define FOD(i, a, b) for(int i = (a); i >= (b); i--)
#define file(name) if(fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define fi first
#define se second
#define el cout << '\n'
#define maxn int(1e5 + 5)
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int LOG = 17;
int n, m, q;
int s[maxn], t[maxn], x[maxn];
ll y[maxn];
int now, tin[maxn], tout[maxn], ver[maxn];
int d[maxn], par[maxn][20];
int l[maxn], r[maxn], res[maxn];
pii e[maxn];
vector<pii> adj[maxn];
vector<int> query[maxn];
int lca(int u, int v) {
if(d[u] < d[v]) swap(u, v);
int k = d[u] - d[v];
FOD(i, LOG, 0) if(k >> i & 1) u = par[u][i];
if(u == v) return u;
FOD(i, LOG, 0) if(par[u][i] != par[v][i]) u = par[u][i], v = par[v][i];
return par[u][0];
}
struct FenwickTree {
int n;
vector<ll> t;
FenwickTree(int __n = 0) {
n = __n;
t.assign(n + 3, 0);
}
void update(int x, int v) {
for(; x <= n; x += x & -x) t[x] += v;
}
void update(int l, int r, int x) {
update(l, x);
update(r + 1, -x);
}
ll get(int x) {
ll res = 0;
for(; x; x -= x & -x) res += t[x];
return res;
}
ll get(int u, int v) {
return get(tin[u]) + get(tin[v]) - (get(tin[lca(u, v)]) << 1);
}
} sum, cnt;
void dfs(int u) {
tin[u] = ++now;
for(pii x : adj[u]) {
int v = x.fi, id = x.se;
if(v != par[u][0]) {
ver[id] = v;
par[v][0] = u;
d[v] = d[u] + 1;
dfs(v);
}
}
tout[u] = now;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m >> q;
FOR(i, 1, n - 1) {
int u, v;
cin >> u >> v;
adj[u].push_back({ v, i });
adj[v].push_back({ u, i });
}
FOR(i, 1, m) cin >> e[i].se >> e[i].fi;
FOR(i, 1, q) cin >> s[i] >> t[i] >> x[i] >> y[i];
sort(e + 1, e + m + 1);
dfs(1);
FOR(i, 1, LOG)
FOR(u, 1, n) par[u][i] = par[par[u][i - 1]][i - 1];
FOR(i, 1, q) l[i] = 0, r[i] = m, res[i] = -1;
while(1) {
bool check = 0;
FOR(i, 1, q) if(l[i] <= r[i]) {
check = 1;
int mid = (l[i] + r[i]) >> 1;
query[mid].push_back(i);
}
if(!check) break;
sum = cnt = FenwickTree(n);
FOR(mid, 0, m) {
if(mid) {
sum.update(tin[ver[e[mid].se]], tout[ver[e[mid].se]], e[mid].fi);
cnt.update(tin[ver[e[mid].se]], tout[ver[e[mid].se]], 1);
}
for(int id : query[mid]) {
if(sum.get(s[id], t[id]) <= y[id]) res[id] = cnt.get(s[id], t[id]), l[id] = mid + 1;
else r[id] = mid - 1;
}
query[mid].clear();
}
}
FOR(i, 1, q) cout << max(-1LL, x[i] - (cnt.get(s[i], t[i]) - res[i])), el;
return 0;
}
