import numpy as np


def conv(xs):
    n = xs.shape[0]
    ys = np.zeros(n - 2, dtype=np.int32)
    d0 = xs[0:-2] - xs[1:-1]
    d1 = xs[1:-1] - xs[2:]
    d0 = (d0 + 3) % 3
    d1 = (d1 + 3) % 3

    ys[(d0 == 1) * (d1 == 1)] = 2
    ys[(d0 == 2) * (d1 == 2)] = 1

    return ys


def main():
    n = int(input())
    xs = np.array(list(map(int, input().split())), dtype=np.int32)

    xs = conv(xs)

    if n == 1:
        return xs[0]

    # 1 0 2 0 1 0 2 0 1
    #   2 0 1 0 2 0 1

    r = (len(xs) - 1) // 2
    if not np.all(xs[1::2] == 0):
        return 0

    if (
        np.all(xs[0::4] == 1) and np.all(xs[2::4] == 2)
    ) or (
        np.all(xs[0::4] == 2) and np.all(xs[2::4] == 1)
    ):
        if r % 2 == 0:
            return xs[0]
        else:
            return 3 - xs[0]

    return 0


print(main())