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 {

	final static long MOD = 1000000007;
	public static void main(String[] args) throws Exception {
		// TODO 自動生成されたメソッド・スタブ

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String W = in.readLine();

		long N = Long.parseLong(W);
		String A = in.readLine();
		String B = in.readLine();
		String C = in.readLine();

		long ans = 0;
		for(int i=0;i<N;i++){
			if(A.charAt(i)==B.charAt(i) && A.charAt(i)==C.charAt(i)){

			}else if(A.charAt(i)==B.charAt(i) || A.charAt(i)==C.charAt(i) ||B.charAt(i)==C.charAt(i)){
				ans++;
			}else{
				ans+=2;
			}
		}
		System.out.println(ans);
	}
}
