//Huyduocdithitp
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/hash_policy.hpp>
typedef int ll;
#define pii pair<ll, ll>
#define fi first
#define se second
#define faster ios_base::sync_with_stdio(false);cin.tie(NULL);
#define N 100005
#define endl '\n'
using namespace std;
using namespace __gnu_pbds;
bool ghuy4g;
const ll inf = 1e9;
const ll S = 320;
ll n, m, q, c[N], d[N], dp[N];
vector<ll> adj[N], adj_2[N];
vector<pii> vt[N]; // vt[u][0] la con {len, u} xa nhat
void pre() {
for (int u = 1; u <= n; u ++) {
gp_hash_table<ll, ll> mp;
for (auto v : adj_2[u]) {
for (auto it : vt[v]) {
mp[it.se] = max(mp[it.se], it.fi + 1);
}
}
vt[u].push_back({0, u});
for (auto it : mp) {
vt[u].push_back({it.se, it.fi});
}
sort(vt[u].begin(), vt[u].end(), greater<pii>());
if (vt[u].size() > S + 1) {
vt[u].resize(S + 1);
}
}
}
bool is[N];
void solve1(ll u, ll k) {
for (int i = 1; i <= k; i ++) {
cin >> d[i];
is[d[i]] = 1;
}
ll ans = -1;
for (int i = 0; i < (ll)vt[u].size(); i ++) {
if (is[vt[u][i].se] == 0) {
ans = max(ans, vt[u][i].fi);
// break;
}
}
//if (ans == 0) ans --;
cout << ans << endl;
for (int i = 1; i <= k; i ++) {
is[d[i]] = 0;
}
}
void solve2(ll u, ll k) {
for (int i = 1; i <= k; i ++) {
cin >> d[i];
is[d[i]] = 1;
}
dp[u] = 0;
for (int i = u - 1; i >= 1; i --) {
dp[i] = -inf;
for (auto v : adj[i]) {
if (v > u) continue;
dp[i] = max(dp[i], dp[v] + 1);
}
}
ll ans = -1;
for (int i = 1; i <= u; i ++) {
if (is[i]) continue;
ans = max(ans, dp[i]);
}
cout << ans << endl;
for (int i = 1; i <= k; i ++) {
is[d[i]] = 0;
}
}
void solve() {
for (int i = 1; i <= q; i ++) {
ll u, yj;
cin >> u >> yj;
if (yj <= S) {
solve1(u, yj);
}
else {
solve2(u, yj);
}
}
}
bool klinh;
signed main(void) {
faster;
cin >> n >> m >> q;
for (int i = 1; i <= m; i ++) {
ll u, v;
cin >> u >> v;
adj[u].push_back(v);
adj_2[v].push_back(u);
}
pre();
solve();
cerr << fabs(&klinh - &ghuy4g) / 1048576.0;
return 0;
}
