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
import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] s=new String[3];
        sc.nextInt();
        for(int i=0;i<3;i++){
            s[i]=sc.next();
        }
        char[] c=new char[3];
        int output=0;
        int tmp=0;
        for(int i=0;i<s[0].length();i++){
            for(int j=0;j<3;j++){
                c[j]=s[j].charAt(i);
            }
            tmp=2;
            if(c[0]==c[1])tmp-=1;
            if(c[0]==c[2])tmp-=1;
            if(c[1]==c[2])tmp=tmp==0?0:tmp-1;
            output+=tmp;
        }
        System.out.println(output);

    }

}