def f(t):
    if t in [[0,1,2],[1,2,0],[2,0,1]]:
        return 1
    elif t in [[2,1,0],[1,0,2],[0,2,1]]:
        return 2
    return 0

N = int(input())
A = list(map(int, input().split()))
if N == 1:
    print(f(A))
    exit()
    
ans = [-1] * 4
for i in range(2 * N + 1):
    if A[i] != ans[i%4] and ans[i%4] != -1:
        print(0)
        exit()
    ans[i%4] = A[i]
    
if ans in [[0,1,2,1],[1,2,0,2],[2,0,1,0]]:
    if N % 2:
        print(1)
    else:
        print(2)
elif ans in [[0,2,1,2],[1,0,2,0],[2,1,0,1]]:
    if N % 2:
        print(2)
    else:
        print(1)
else:
    print(0)