Frequent Alphabet

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.

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.

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