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.Scanner;

class Main{
public static void main(String args[]){
Scanner s=new Scanner(System.in);
int n=s.nextInt();
char[][] w=new char[3][n];
for(int i=0;i<3;i++){
String input=s.next();
w[i]=input.toCharArray();
}
int count=0;
for(int i=0;i<n;i++){
if((w[0][i]==w[1][i]||w[1][i]==w[2][i])||w[0][i]==w[2][i]){
count++;
}
if((w[0][i]==w[1][i]&&w[1][i]==w[2][i])&&w[0][i]==w[2][i]){
count++;
}
}
System.out.println(n*2-count);
}
}