#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pli = pair< long long, int >;
using pii = pair< int, int >;
struct query {
int t, y, i;
vector< int > c;
};
const int N = 1e5 + 7;
int n, m, Q, res;
vector< int > g[N];
query q[N];
int d[N];
bool notvisit[N];
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
// freopen("BITARO.inp", "r", stdin);
// freopen("BITARO.out", "w", stdout);
cin >> n >> m >> Q;
for (int i = 1; i <= m; ++i) {
int u, v;
cin >> u >> v;
g[v].push_back(u);
}
for (int i = 1; i <= Q; ++i) {
int tmp;
cin >> q[i].t >> q[i].y;
for (int j = 1; j <= q[i].y; ++j) {
cin >> tmp;
// if (tmp <= q[i].t)
// q[i].c.push_back(tmp);
notvisit[tmp] = true;
}
q[i].i = i;
}
d[ q[1].t ] = 1;
for (int u = q[1].t; u; --u) {
if (!d[u]) continue;
for (int v : g[u])
d[v] = max(d[v], d[u] + 1);
if (!notvisit[u])
res = max(res, d[u]);
}
--res;
if (!res && notvisit[ q[1].t ])
res = -1;
cout << res;
return 0;
}
