from bisect import bisect_right
n=int(input().split())

memo=[]
for _ in range(n):
    memo.append(input())
memo.sort()

m=''.join(memo)
infi=1<<40
dp=[infi]*(2*10**5+100)
dp[0]=-infi
for i in range(len(m)):
    s=ord(m[i])-ord('a')
    pos = bisect_right(dp,s)
    dp[pos]=s

ans= bisect_right(dp,infi-1)

print(ans)