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.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
    public static void main(String args[]) throws Exception{
        BufferedReader stdR = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(stdR.readLine());
        String A = stdR.readLine();
        String B = stdR.readLine();
        String C = stdR.readLine();
        int count = 0;
        for(int i = 0 ; i < N ; i++) {
            if(A.charAt(i) == B.charAt(i)) {
                if(A.charAt(i) != C.charAt(i)) {
                    count += 1;
                }
            }else if(A.charAt(i) == C.charAt(i)) {
                count += 1;
            }else if(B.charAt(i) == C.charAt(i)) {
                count += 1;
            }else {
                count += 2;
            }
        }
        System.out.println(count);
    }
}
