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.math.BigInteger;
import java.util.*;

public class Main {
	int INF = 1 << 29;
	
	
	private void doit(){
		Scanner sc = new Scanner(System.in);
		while(sc.hasNext()){
			int n = sc.nextInt();
			String [] data = new String[3];
			for(int i = 0; i < 3; i++){
				data[i] = sc.next();
			}
			int count = 0;
			for(int i = 0; i < n; i++){
				int [] freq = new int[26];
				freq[data[0].charAt(i) - 'a']++;
				freq[data[1].charAt(i) - 'a']++;
				freq[data[2].charAt(i) - 'a']++;
				int res = Math.max(freq[data[0].charAt(i) - 'a'], Math.max(freq[data[1].charAt(i) - 'a'], freq[data[2].charAt(i) - 'a']));
				count += 3 - res;
			}
			System.out.println(count);
			
		}
	}


	private void debug(Object... o) {
		System.out.println("debug = " + Arrays.deepToString(o));
	}

	public static void main(String[] args) {
		new Main().doit();
	}

}
