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문제

Your social media account has just been hacked, and you are advised to change your password. You have two favorite strings S and T, each contains exactly N lowercase alphabets. You want the new password to be some combinations of these two strings. Specifically, the new password P should contain N alphabets such that the ith character of P is either the ith character of S or the ith character of T.

For example, let S = “icyz” and T = “ixpc”. There are 8 different possible new passwords which you can choose: “icyz”, “icyc”, “icpz”, “icpc”, “ixyz”, “ixyc”, “ixpz”, and “ixpc”.

The score of a password P is defined as the number of occurences of the most frequent alphabet in P. For example, let P = “icpc”. The password “icpc” has one occurence of ‘i’, two occurences of ‘c’, and one occurence of ‘p’. The most frequent alphabet in P is ‘c’ with the number of occurences of 2. Therefore, the score of “icpc” is 2.

Given two strings S and T, your task is to find the highest score you can get for your new password.

입력

Input begins with a line containing an integer: N (1 ≤ N ≤ 100 000) representing the length of the password. The next line contains a string S containing N lowercase alphabets representing your first favorite string. The next line contains a string T containing N lowercase alphabets representing your second favorite string.

출력

Output in a line an integer representing the highest score you can get for your new password.

예제 입력 1

4
icyz
ixpc

예제 출력 1

2

These two strings are given as an illustration in the problem description as well as all its possible new passwords. Among them, the passwords “icyc” and “icpc” have the highest score of 2, while the other remaining passwords have a score of 1.

예제 입력 2

11
goodluckfor
contestants

예제 출력 2

3

예제 입력 3

14
helpiamtrapped
inanincfactory

예제 출력 3

4