#include <bits/stdc++.h>
#if defined(__GNUC__)
#pragma GCC optimize ("Ofast")
#endif
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<x<<endl;
#define debugp(x) cerr<<#x<<"= {"<<x.first<<", "<<x.second<<"}"<<endl;
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;
#define SZ(x) ((int) x.size())
const ld eps=1e-7;
const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod = 1000000007;
const int MAXN = 100010, SQ=320;
int n, m, q, u, v, x, y, t, a, b, ans;
vector<pii> good[MAXN];
int dp[MAXN];
vector<int> G[MAXN];
unordered_map<int, int> mp;
bool mark[MAXN];
void merg(int a, int b){
vector<pii> tmp;
int sz=min(SZ(good[a])+SZ(good[b])-1, SQ);
for (int i=0, j=0, t=0; i+j<SZ(good[a])+SZ(good[b]);){
pii pp={good[b][j].first+1, good[b][j].second};
if (good[a][i]>pp) tmp.pb(good[a][i++]);
else tmp.pb(pp), j++;
if (mark[tmp.back().second]) tmp.pop_back();
else t++;
if (t>=sz) break ;
}
good[a].clear();
for (pii p:tmp)/* if (!mark[p.second])*/{
good[a].pb(p);
//mark[p.second]=1;
//if (good[a].size()>SQ) break ;
}
for (pii p:good[a]) mark[p.second]=0;
}
void bigquery(){
while (y--){
cin>>x;
dp[x]=-inf;
}
for (int i=1; i<=v; i++) for (int j:G[i]) dp[i]=max(dp[i], dp[j]+1);
if (dp[v]<0) dp[v]=-1;
cout<<dp[v]<<'\n';
memset(dp, 0, sizeof(dp));
}
int smallquery(){
set<int> st;
while (y--){
cin>>x;
st.insert(x);
}
for (pii p:good[v]){
if (st.count(p.second)) continue ;
if (p.first<0) kill(-1);
kill(p.first);
}
cout<<"-1\n";
}
int badquery(){
while (y--) cin>>x;
cout<<"-1\n";
}
void query(){
cin>>v>>y;
if (y>=SQ-10) bigquery();
else if (y > (int)good[v].size()+5) badquery();
else smallquery();
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
cin>>n>>m>>q;
while (m--){
cin>>u>>v;
G[v].pb(u);
}
for (int i=1; i<=n; i++){
good[i].pb({0, i});
good[i].pb({-inf, 0});
for (int j:G[i]) merg(i, j);
}
while (q--) query();
return 0;
}
/*
5 6 3
1 2
2 4
3 4
1 3
3 5
4 5
4 1 1
5 2 2 3
2 3 1 4 5
*/
