n = int(input())
arr = list(map(int, input().split()))

# Algo
i = 0
maxLen = 1
arr.append(1e10)  # Sentinel
n += 1
for j in range(n-1):
    if abs(arr[j+1]-arr[j]) > 1:
        maxLen = max(maxLen, j - i + 1)
        i = j + 1

print(maxLen)