#include <bits/stdc++.h>
using namespace std;
template<class T, class U>
void ckmin(T &a, U b)
{
if (a > b) a = b;
}
template<class T, class U>
void ckmax(T &a, U b)
{
if (a < b) a = b;
}
#define MP make_pair
#define PB push_back
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define SZ(x) ((int) (x).size())
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, a, b) for (auto i = (a); i < (b); i++)
#define FORD(i, a, b) for (auto i = (a) - 1; i >= (b); i--)
const int MAXN = 250013;
const int INF = 1e9 + 7;
const int DELTA = 126;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
int N, M, K;
vi edge[MAXN];
pii ban[MAXN];
int dist[MAXN], cc[MAXN];
bitset<DELTA + 3> seen[MAXN];
queue<pii> q;
int32_t main()
{
cout << fixed << setprecision(12);
cerr << fixed << setprecision(4);
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> N >> M;
FOR(i, 0, M)
{
int u, v;
cin >> u >> v; u--; v--;
edge[u].PB(v);
edge[v].PB(u);
}
FOR(i, 0, N)
{
edge[i].PB(i);
cc[i] = -1;
}
cin >> K;
FOR(i, 0, K)
{
int c; cin >> c;
vi s(c);
FOR(j, 0, c)
{
cin >> s[j]; s[j]--;
ban[s[j]] = {j, c};
cc[s[j]] = i;
}
}
fill(dist, dist + N, INF);
dist[0] = 0;
q.push({0, 0});
while(!q.empty())
{
int d = q.front().fi, u = q.front().se; q.pop();
if (d - dist[u] >= DELTA) continue;
// cerr << d << ' ' << u << endl;
if (seen[u][d - dist[u]]) continue;
seen[u][d - dist[u]] = true;
for (int v : edge[u])
{
if (cc[v] != -1)
{
// cerr << "check " << d + 1 << ' ' << v << endl;
int m = ban[v].se;
if ((d + 1) % ban[v].se == ban[v].fi) continue;
if (cc[u] == cc[v] && (d + 1) % m == ban[u].fi && d % m == ban[v].fi) continue;
}
if (dist[v] > d + 1)
{
dist[v] = d + 1;
}
// cerr << u << ' ' << v << ' ' << d + 1 << endl;
q.push({d + 1, v});
//you can go from u -> v at time t iff:
//t != ban[v].fi mod ban[v].se
//t-1 != ban[u][v].fi mod ban[u][v].se
}
}
if (dist[N - 1] >= INF)
{
cout << "impossible\n";
return 0;
}
cout << dist[N - 1] << '\n';
return 0;
}
