You are given two binary strings \(A\) and \(B\) and are required to make \(A\) equals to \(B\). There are two types of operations:

1. Swap any two adjacent bits or characters in string \(A\). The cost of this operation is 1 unit.
2. Flip the bit or character of the string. The cost of this operation is 1 unit.

What is the minimum cost to make string \(A\) equal to \(B\)?

Input format

• The first line contains one integer that denotes the length of both strings.
• The next two lines take two strings \(A\) and \(B\) of length \(n\) as an input.

Output format

Print one integer that represents the minimum cost required to convert string \(A\) to string \(B\).

Constraints

\(1 \le n \le 10^{5}\)

Note

The length of both the strings \(A\) and \(B\) is always the same.