n=int(input())
a=[int(input()) for _ in range(n)]
a.sort()
from bisect import bisect_left as b
ary=[a[0]]
for x in a[1:]:
  idx=b(ary,x-1)
  if idx==len(ary):
    ary[-1]=x
  elif idx==0:
    ary.append(x)
  else:
    ary[idx]=x
print(len(ary))