// In the name of the God
#include <bits/stdc++.h>
#define ll long long
#define int long long
#define pb push_back
#define F first
#define S second
#define mp make_pair
#define pii pair <int, int>
#define smin(x, y) (x) = min((x), (y))
#define smax(x, y) (x) = max((x), (y))
#define all(x) (x).begin(), (x).end()
using namespace std;
const int inf = 1e9+7;
const int mod = 998244353;
const int maxn = 1e5+5, lg = 17, sq = 700;
struct Q {
int s, t, x, y, cnt = 0;
} qs[maxn];
int n, m, q, ti = 0, fr[maxn], to[maxn], in[maxn], out[maxn], h[maxn];
int mark[maxn], mark2[maxn];
pair <int, pii> par[lg][maxn];
vector <int> adj[maxn], handle;
vector <pii> ch;
void dfs1(int v = 0, int p = 0) {
in[v] = ti++;
for (int u : adj[v]) {
if (u != p) {
h[u] = h[v]+1; dfs1(u, v);
}
}
out[v] = ti;
}
void dfs2(int v = 0, int p = 0) {
par[0][v].F = p;
for (int i = 1; i < lg; i++) {
int u = par[i-1][v].F;
par[i][v] = mp(par[i-1][u].F,
mp(par[i-1][v].S.F+par[i-1][u].S.F, par[i-1][v].S.S+par[i-1][u].S.S));
}
for (int u : adj[v]) {
if (u != p) dfs2(u, v);
}
}
pii lca(int v, int u) {
pii res(0, 0);
if (h[v] < h[u]) swap(v, u);
int d = h[v]-h[u];
for (int i = 0; i < lg; i++) {
if (d&(1<<i)) {
res.F += par[i][v].S.F, res.S += par[i][v].S.S;
v = par[i][v].F;
}
}
if (v == u) return res;
for (int i = lg-1; i >= 0; i--) {
if (par[i][v].F != par[i][u].F) {
res.F += par[i][v].S.F+par[i][u].S.F, res.S += par[i][v].S.S+par[i][u].S.S;
v = par[i][v].F, u = par[i][u].F;
}
}
res.F += par[0][v].S.F+par[0][u].S.F, res.S += par[0][v].S.S+par[0][u].S.S;
return res;
}
bool is (int v, int u) {
return in[v] <= in[u] and out[v] >= out[u];
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m >> q;
for (int i = 0; i < n-1; i++) {
cin >> fr[i] >> to[i];
adj[--fr[i]].pb(--to[i]);
adj[to[i]].pb(fr[i]);
}
dfs1();
for (int i = 0; i < m; i++) {
int p, c; cin >> p >> c;
p--;
int v = fr[p];
if (in[v] < in[to[p]]) v = to[p];
ch.pb(mp(c, v));
}
for (int i = 0; i < q; i++) {
cin >> qs[i].s >> qs[i].t >> qs[i].x >> qs[i].y;
qs[i].s--, qs[i].t--;
}
sort(all(ch));
for (int i = 0; i < m; i++) {
par[0][ch[i].S].S.F++, par[0][ch[i].S].S.S += ch[i].F;
if (i != m-1 and (i%sq ) != (sq-1)) continue;
dfs2();
for (int j = 0; j < q; j++) {
if (mark[j]) continue;
pii p = lca(qs[j].s, qs[j].t);
if (p.S >= qs[j].y) {
handle.pb(j); mark[j] = 1;
}
else qs[j].y -= p.S, qs[j].cnt += p.F;
}
for (int j = (i/sq)*sq; j <= i; j++) {
assert(j-i+1 <= sq);
int v = ch[j].S, w = ch[j].F;
for (int k : handle) {
if (is(v, qs[k].s) != is(v, qs[k].t)) {
if (w <= qs[k].y) qs[k].y -= w, qs[k].cnt++;
}
}
}
handle.clear();
for (int j = 0; j < n; j++) par[0][j].S = mp(0, 0);
}
for (int i = 0; i < m; i++) par[0][ch[i].S].S.F++, par[0][ch[i].S].S.S += ch[i].F;
dfs2();
for (int i = 0; i < q; i++) {
int res = lca(qs[i].s, qs[i].t).F-qs[i].cnt;
if (res <= qs[i].x) cout << qs[i].x-res << '\n';
else cout << -1 << '\n';
}
return 0;
}
