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.io.PrintWriter;
import static java.lang.Integer.*;
import static java.lang.Long.*;
import static java.lang.Math.*;
import static java.lang.System.*;

public class Main {
	public static int MOD = 1000000007;
	public static void main(String[] args) {
		int i,j;
		Scanner sc = new Scanner(in);
		int n = parseInt(sc.next());
		char[] a = sc.next().toCharArray();
		char[] b = sc.next().toCharArray();
		char[] c = sc.next().toCharArray();
		sc.close();
		int cnt=0;
		for(i=0;i<n;i++) {
			if(a[i]==b[i]) {
				if(b[i]!=c[i]) {
					cnt++;
				}
			} else {
				if(b[i]==c[i]) {
					cnt++;
				} else if(a[i]==c[i]) {
					cnt++;
				} else {
					cnt+=2;
				}
			}
		}
		out.println(cnt);
	}
}
