Touitsu

You are given three strings A, B and C. Each of these is a string of length N consisting of lowercase English letters.

Our objective is to make all these three strings equal. For that, you can repeatedly perform the following operation:

• Operation: Choose one of the strings A, B and C, and specify an integer i between 1 and N (inclusive). Change the i-th character from the beginning of the chosen string to some other lowercase English letter.

What is the minimum number of operations required to achieve the objective?

Constraints

• 1 \leq N \leq 100
• Each of the strings A, B and C is a string of length N.
• Each character in each of the strings A, B and C is a lowercase English letter.

Input

Input is given from Standard Input in the following format:

N A B C

Output

Print the minimum number of operations required.

Examples

Input

4 west east wait

Output

3

Input

9 different different different

Output

0

Input

7 zenkoku touitsu program

Output

13

inputFormat

Input

Input is given from Standard Input in the following format:

N A B C

outputFormat

Output

Print the minimum number of operations required.

Examples

Input

4 west east wait

Output

3

Input

9 different different different

Output

0

Input

7 zenkoku touitsu program

Output

13

样例

9
different
different
different

0