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.*;
import java.lang.*;
import java.io.*;
 
class Main {
  public static void main(String args[]) {
    Scanner scanner = new Scanner(System.in);
 
    String input1 = scanner.nextLine();
    String A = scanner.nextLine();
    String B = scanner.nextLine();
    String C = scanner.nextLine();
 

int N = Integer.parseInt(input1);

int count = 0;

String AN = "";
String BN = "";
String CN = "";

for(int i=0; i<N;i++){
AN = A.substring(i,i+1);
BN = B.substring(i,i+1);
CN = C.substring(i,i+1);

if(!AN.equals(BN)){
if(!BN.equals(CN)){
count++;
count++;
if(AN.equals(CN)){
count--;
}
}else{
count++;
}
}else{
if(!AN.equals(CN)){
count++;
}else if(!BN.equals(CN)){
count++;
}
}
}

    System.out.print(count);
    scanner.close();
  }
}