mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    def f(a, b, c):
        if (a+1)%3 == b and (b+1)%3 == c and (c+1)%3 == a:
            return 1
        elif (a+1)%3 == c and (c+1)%3 == b and (b+1)%3 == a:
            return 2
        else:
            return 0

    N = int(input())
    A = list(map(int, input().split()))

    if N == 1:
        print(f(A[0], A[1], A[2]))
    elif N == 2:
        B = []
        for i in range(3):
            B.append(f(A[i], A[i+1], A[i+2]))
        print(f(B[0], B[1], B[2]))
    else:
        B = []
        for i in range(2 * N - 1):
            B.append(f(A[i], A[i + 1], A[i + 2]))
        ok = 1
        for i in range(N * 2 - 1):
            if i & 1:
                if B[i] != 0:
                    ok = 0
            else:
                if B[i] == 0:
                    ok = 0
                if i > 0:
                    if B[i] == B[i-2]:
                        ok = 0
        if ok:
            if N & 1:
                print(B[0])
            else:
                print(B[0] ^ 3)
        else:
            print(0)


if __name__ == '__main__':
    main()