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
#include<cstdio>
char a[105],b[105],c[105];

int main(){
    int n;
    scanf("%d%s%s%s",&n,a+1,b+1,c+1);
    int ans = 0;
    for(int i = 1; i <= n; i++){
        if(a[i]==b[i] && b[i]==c[i]) continue;
        else if(a[i]==b[i] || a[i]==c[i] || b[i]==c[i]) ans++;
        else ans += 2;
    }
    printf("%d\n",ans);
    return 0;
}
