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);
        int N = sc.nextInt();
        String a = sc.next();
        String b = sc.next();
        String c = sc.next();
        int [] List = new int[N];
        for(int num=0;num<N;num++){
            int k =0;
            if(a.charAt(num)==b.charAt(num)) k++;
            if(a.charAt(num)==c.charAt(num))k++;
            if(b.charAt(num)==c.charAt(num))k++;
            if(k==0)List[num]=2;
            else if(k==1) List[num]=1;
        }
        int sum=0;
        for(int d=0;d<N;d++) sum+=List[d];
        System.out.println(sum);
    }
}
