#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define fi first
#define se second
#define pb push_back
#define p_q priority_queue
#define bit(n, i) (((n)>>(i))&1)
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,int> pli;
typedef vector <vector <int> > vvi;
const int M = 1e5 + 6;
const int mod = 1e9 + 7;
const int inf = 1e9 + 7;
void maximize (int &a, int b) { if (a < b) a = b; }
void minimize (int &a, int b) { if (a > b) a = b; }
void add (int &a, int b) { a += b; if (a >= mod) a -= mod; }
void del (int &a, int b) { a -= b; if (a < 0) a += mod; }
int n, m, q;
vector <int> g[M];
pii e[M], t[M];
int cost[M], in[M], out[M], tt[M], dem[M];
int anc[M][18], depth[M];
int d[M], ini[M], Lca[M];
int timedfs = 0;
int L[M], R[M], MID[M];
ll 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; for (int i = 1; i <= n; i ++) f[i] = 0; }
void update (int i, int val) { while (i <= n) { f[i] += val; i += i & (-i); } }
ll GET (int i) { ll res = 0; while (i > 0) { res += f[i]; i -= i & (-i); } return res; }
ll get (int l, int r) { return GET (r) - GET (l - 1); }
} BIT, CNT;
void dfs (int u, int parent)
{
in[u] = ++ timedfs;
tt[timedfs] = u;
for (int &v : g[u])
{
if (v == parent) continue;
anc[v][0] = u;
depth[v] = depth[u] + 1;
dfs (v, u);
}
out[u] = timedfs;
}
int LCA (int u, int v)
{
if (depth[u] < depth[v]) swap (u, v);
while (depth[u] > depth[v])
{
int k = __lg (depth[u] - depth[v]);
u = anc[u][k];
}
if (u == v) return u;
int k = __lg (depth[u]);
while (k >= 0)
{
if (anc[u][k] != anc[v][k])
{
u = anc[u][k];
v = anc[v][k];
}
k --;
}
return anc[u][0];
}
void prework (int u, int parent)
{
for (int &v : g[u])
{
if (v == parent) continue;
d[v] += d[u];
prework (v, u);
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
// freopen (".inp", "r", stdin);
// freopen (".out", "w", stdout);
cin >> n >> m >> q;
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};
}
for (int i = 1; i <= m; i ++)
{
int p, c; cin >> p >> c;
t[i] = {c, p};
}
for (int i = 1; i <= q; i ++)
{
int s, t; ll x, y; cin >> s >> t >> x >> y;
Q[i] = {s, t, x, y};
ans[i] = -1;
}
dfs (1, 0);
int kmax = __lg (n);
for (int k = 1; k <= kmax; k ++)
for (int i = 1; i <= n; i ++)
anc[i][k] = anc[anc[i][k - 1]][k - 1];
for (int i = 1; i < n; i ++)
if (e[i].fi != anc[e[i].se][0]) swap (e[i].fi, e[i].se);
sort (t + 1, t + m + 1);
for (int i = 1; i <= m; i ++)
{
int id = e[t[i].se].se;
d[id] ++;
}
prework (1, 0);
for (int i = 1; i <= q; i ++)
{
int u = Q[i].s, v = Q[i].t;
int lca = LCA (u, v);
ini[i] = d[u] + d[v] - 2 * d[lca];
Lca[i] = lca;
}
for (int i = 1; i <= q; i ++)
L[i] = 0, R[i] = m;
while (true)
{
vector <int> Query;
for (int i = 1; i <= q; i ++)
{
if (L[i] > R[i]) continue;
MID[i] = (L[i] + R[i]) / 2;
Query.pb (i);
}
if (Query.empty()) break;
sort (all (Query), [] (int a, int b) {
return MID[a] < MID[b];
});
BIT.resize (n + 2);
CNT.resize (n + 2);
int pt = 1;
for (int &i : Query)
{
int ss = Q[i].s, tt = Q[i].t;
ll x = Q[i].x, y = Q[i].y;
while (pt <= MID[i])
{
int v = e[t[pt].se].se, val = t[pt].fi;
BIT.update (in[v], val);
BIT.update (out[v] + 1, -val);
CNT.update (in[v], 1);
CNT.update (out[v] + 1, -1);
pt ++;
}
ll lmao = BIT.GET (in[ss]) + BIT.GET (in[tt]) - 2 * BIT.GET (in[Lca[i]]);
ll sl = CNT.GET (in[ss]) + CNT.GET (in[tt]) - 2 * CNT.GET (in[Lca[i]]);
if (lmao <= y)
{
ans[i] = max (ans[i], x - ini[i] + sl);
L[i] = MID[i] + 1;
}
else R[i] = MID[i] - 1;
}
}
for (int i = 1; i <= q; i ++)
cout << ans[i] << endl;
return 0;
}
