Problem:
Score : 200 points

Problem Statement

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.

Sample Input 1

4
west
east
wait

Sample Output 1

3

In this sample, initially A = west、B = east、C = wait. We can achieve the objective in the minimum number of operations by performing three operations as follows:

Change the second character in A to a. A is now wast.

Change the first character in B to w. B is now wast.

Change the third character in C to s. C is now wast.

Sample Input 2

9
different
different
different

Sample Output 2

0

If A, B and C are already equal in the beginning, the number of operations required is 0.

Sample Input 3

7
zenkoku
touitsu
program

Sample Output 3

13

Solution in C (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int max(int a, int b){
	return a >= b ? a : b;
}

int compare_int(const void *a, const void *b){
    return *(int*)a - *(int*)b;
}

int euclid(int a, int b){
  if(a < b){
    int tmp = a;a = b;b = tmp;
  }
  int r = a % b;
  if(r < 0) r += b;
  while(r != 0){
    a = b;b = r;r = a % b;
    if(r < 0) r += b;
  }
  return b;
}

int main(){
  int N,check1=0,check2=0,check3=0,count=0;
  scanf("%d",&N);
	char a[N],b[N],c[N];
  scanf("%s",a);
  scanf("%s",b);
  scanf("%s",c);
  //printf("%c",a[0]);  printf("%c",b[1]);  printf("%c",c[2]);
	for(int i=0;i<N;i++){
		check1=0;check2=0;check3=0;
		if(a[i]==b[i])check1=1;
		if(b[i]==c[i])check2=1;
		if(c[i]==a[i])check3=1;
		if(check1+check2+check3 >= 2)count = count;
    if(check1+check2+check3 == 1) count++;
		if(check1+check2+check3 == 0) count+=2;
	}
	printf("%d",count);
  return 0;
}