#include <bits/stdc++.h>
using namespace std;
// macros
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> lll;
typedef tuple<int, int, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vll;
typedef vector<lll> vlll;
#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define RE(a,c) REP(a,0,c)
#define RE1(a,c) REP(a,1,c+1)
#define REI(a,b,c) REP(a,b,c+1)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define FOR(a,b) for(auto& a : b)
#define all(a) a.begin(), a.end()
#define INF 1e18
#define EPS 1e-9
#define pb push_back
#define popb pop_back
#define fi first
#define se second
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
// input
template<class T> void IN(T& x) {cin >> x;}
template<class H, class... T> void IN(H& h, T&... t) {IN(h); IN(t...); }
// output
template<class T1, class T2> void OUT(const pair<T1,T2>& x);
template<class T> void OUT(const vector<T>& x);
template<class T> void OUT(const T& x) {cout << x;}
template<class H, class... T> void OUT(const H& h, const T&... t) {OUT(h); OUT(t...); }
template<class T1, class T2> void OUT(const pair<T1,T2>& x) {OUT(x.fi,' ',x.se);}
template<class T> void OUT(const vector<T>& x) {RE(i,x.size()) OUT(i==0?"":" ",x[i]);}
template<class... T> void OUTL(const T&... t) {OUT(t..., "\n"); }
template<class H> void OUTLS(const H& h) {OUTL(h); }
template<class H, class... T> void OUTLS(const H& h, const T&... t) {OUT(h,' '); OUTLS(t...); }
// dp
template<class T> bool ckmin(T&a, T&b) { bool bl = a > b; a = min(a,b); return bl;}
template<class T> bool ckmax(T&a, T&b) { bool bl = a < b; a = max(a,b); return bl;}
void program();
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
program();
}
//===================//
// begin program //
//===================//
const int MX = 3e5;
const int N = (1<<20);
const int SQ = 200;
int n, m, q;
int s[MX], e[MX];
vi pre[MX], nxt[MX];
vii best[MX];
int t, y, c[MX];
int dp[MX];
bitset<MX> used;
void program() {
IN(n,m,q);
RE(i,m) IN(s[i],e[i]);
RE(i,m) pre[e[i]].pb(s[i]);
RE(i,m) nxt[s[i]].pb(e[i]);
// fill best
REP(i,1,n+1) {
priority_queue<iii> pq;
FOR(v,pre[i]) pq.push({best[v][0].fi,v,0});
while(!pq.empty() && (int)best[i].size() < SQ) {
int l, v, j;
tie(l,v,j) = pq.top(); pq.pop();
if(!used[best[v][j].se])
best[i].pb({l+1,best[v][j].se});
used[best[v][j].se] = 1;
if(++j != best[v].size())
pq.push({best[v][j].fi,v,j});
}
best[i].pb({0,i});
FOR(p,best[i]) used[p.se] = 0;
}
// answer queries
RE(_,q) {
IN(t,y);
RE(i,y) IN(c[i]);
RE(i,y) used[c[i]] = 1;
if(y < SQ) {
bool found = 0;
FOR(p,best[t]) {
if(used[p.se]) continue;
OUTL(p.fi);
found = 1;
break;
}
if(!found) OUTL(-1);
} else {
REP(i,1,t+1) dp[i] = -1;
REP(i,1,t+1) {
if(!used[i]) dp[i] = max(0,dp[i]);
if(dp[i] != -1)
FOR(v,nxt[i]) dp[v] = max(dp[v], 1 + dp[i]);
}
OUTL(dp[t]);
}
RE(i,y) used[c[i]] = 0;
}
}
