백준 - 1976 : 여행 가자 (G4)

 1N = int(input())
 2M = int(input())
 3
 4parent = [i for i in range(N)]
 5
 6def find(node):
 7    if parent[node] != node:
 8        parent[node] = find(parent[node])
 9    return parent[node]
10
11def union(a, b):
12    a = find(a)
13    b = find(b)
14    if a < b:
15        parent[b] = a
16    else:
17        parent[a] = b
18
19for i in range(N):
20    for j, item in enumerate(map(int, input().split())):
21        if item:
22            union(i, j)
23
24path = list(map(int, input().split()))
25start = parent[path[0]-1]
26for i in range(1, M):
27    if parent[path[i]-1] != start:
28        print("NO")
29        break
30else:
31    print('YES')