n = int(input())
A = [int(input()) for i in range(n)]

if n == 1:
    print(1)
    exit()

A.sort()
B = [A[0]]
import bisect
for i in range(1, n):
    j = bisect.bisect_left(B, A[i]-1)
    if j == 0:
        B.append(A[i])
    else:
        B[j-1] = A[i]
print(len(B))