import sys
input = sys.stdin.readline
def iinput(): return int(input())
def sinput(): return input().rstrip()
def i0input(): return int(input()) - 1
def linput(): return list(input().split())
def liinput(): return list(map(int, input().split()))
def miinput(): return map(int, input().split())
def li0input(): return list(map(lambda x: int(x) - 1, input().split()))
def mi0input(): return map(lambda x: int(x) - 1, input().split())
INF = 10**20
MOD = 1000000007

N = iinput()
A = liinput()
if N >= 3:
    print(0)
    exit(0)

if N == 2:
    if A == [2, 1, 0, 1, 2]:
        print(1)
    elif A == [1, 2, 0, 2, 1]:
        print(2)
    else:
        print(0)
    exit(0)

if A == [0, 1, 2] or A == [1, 2, 0] or A == [2, 0, 1]:
    print(1)
elif A == [2, 1, 0] or A == [1, 0, 2] or A == [0, 2, 1]:
    print(2)
else:
    print(0)