n = int(input().strip())
a = [int(a_temp) for a_temp in input().strip().split(' ')]
ae = list(a)
ae.remove(max(a))
ae.remove(min(a))
def count(array, a, b):
    return len([i for i in array if a <= i <= b])

ms = []
for i in ae:
    ms += [count(a, i, i + 1)]
    ms += [count(a, i - 1, i)]
print(max(ms))