#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
int sq;
vector<int> w;
bool comp(pair<int, int> a, pair<int, int> b){return a > b;}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, m, q; cin >> n >> m >> q;
sq = sqrt(n+0.0);
w.resize(n, -1);
vector<vector<int>> v(n), vv(n);
for(int i = 0; i < m; i++){
int a, b; cin >> a >> b; a--, b--;
v[b].pb(a);
vv[a].pb(b);
}
vector<vector<pair<int, int>>> dps(n);
for(int i = 0; i < n; i++){
w[i] = 0;
dps[i].pb({-1, i});
for(int x: v[i]){
for(auto [c, nd]: dps[x]){
if(w[nd] == -1) w[nd] = c+1, dps[i].pb({-1, nd});
else w[nd] = max(w[nd], c+1);
}
}
int el = min(sq, (int)dps[i].size());
for(auto &[c, nd]: dps[i]) c = w[nd], w[nd] = -1;
nth_element(dps[i].begin(), dps[i].begin()+el, dps[i].end(), comp);
while(dps[i].size() > sq) dps[i].pop_back();
}
vector<bool> busy(n, 0);
while(q--){
int tj, yj; cin >> tj >> yj;
tj--;
vector<int> cbs(yj);
for(int &x: cbs) cin >> x, x--, busy[x] = 1;
if(yj < sq){
int ans = busy[tj] ? -1 : 0;
for(auto [c, nd]: dps[tj]) if(!busy[nd]) ans = max(ans, c);
cout << ans << "\n";
for(int x: cbs) busy[x] = 0;
continue;
}
vector<int> dp(n, -1);
for(int i = 0; i <= tj; i++){
if(busy[i] && dp[i] == -1) continue;
dp[i] = max(dp[i], 0);
for(int x: vv[i]) dp[x] = max(dp[x], dp[i]+1);
}
cout << dp[tj] << "\n";
for(int x: cbs) busy[x] = 0;
}
}
