n = int(input()) num = list(map(int, input().split())) left = 0 max_length = 0 length = 0 for i in range(1, n): if abs(num[i] - num[i-1]) <= 1: if length > max_length: max_length = length length = i - left + 2 elif abs(num[i] - num[i-1]) > 1: left = i length = i - left + 2 print(max_length)