n = int(input())
L = list(map(int, input().split()))
L.sort()
mini = L[0]
maxi = L[-1]
if mini == maxi:
    print (len(L))
else:
    c = [L.count(x) for x in range(mini, maxi+1)]
    nc = [c[x]+c[x+1] for x in range(len(c)-1)]
    print (max(nc))