import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")

n = int(input())
a = [int(input()) for _ in range(n)]
a.sort()
ans = 0
j = 0
for i in range(n):
    while j+1<n and a[j+1]<=a[i]+1:
        j += 1
    ans = max(ans, j-i+1)
print(ans)