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[] ) {

		int N;
		String A,B,C;
		int counter;
		
		Scanner scan = new Scanner( System.in );
		N = scan.nextInt();
		A = scan.next();
		B = scan.next();
		C = scan.next();
		
		
		counter = 0;
		
		for( int i = 0; i < A.length(); i ++ ) {
			if( A.charAt(i) != B.charAt(i) && A.charAt(i) != C.charAt(i)) {
				if( B.charAt(i) != C.charAt(i))
					counter += 2;
				else {
					counter++;
				}
			}
			else if(A.charAt(i) != B.charAt(i) || A.charAt(i) != C.charAt(i) ) {
				counter++;
			}
			
			//System.out.println( i +":" + counter);
		}
		
				
		System.out.println( counter  );
		
		scan.close();
		
	}
}