#include using namespace std; #define rep(i, n) for (int i = 0; i < (int)(n); i++) int main() { int N, M; cin >> N >> M; vector> edges(N); rep(i, M) { int u, v; cin >> u >> v; u--, v--; edges[u].push_back(v), edges[v].push_back(u); } int K; cin >> K; vector is_iwai(N, false); rep(i, K) { int A; cin >> A; is_iwai[A - 1] = true; } const int INF = INT32_MAX; // dists[i][j][k] := 岩井星人に連続でk回会ったうえで座標(i, j)に到達するまでの最短距離 vector> dists(N, vector(5, INF)); queue> qu; qu.push({0, 0}); dists[0][0] = 0; while (qu.size()) { auto [now, i_cnt] = qu.front(); qu.pop(); for (int next : edges[now]) { int next_i_cnt = is_iwai[next] ? i_cnt + 1 : 0; // 次の移動で岩井星人に連続5回会う if (5 <= next_i_cnt) { continue; } // 最短距離を更新しない移動 if (dists[next][next_i_cnt] <= dists[now][i_cnt] + 1) { continue; } dists[next][next_i_cnt] = dists[now][i_cnt] + 1; qu.push({next, next_i_cnt}); } } int ans = dists[N - 1][0]; if (ans == INF) { cout << -1 << endl; } else { cout << ans << endl; } return 0; }