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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

"use strict";
const Main = (input) =>{
   let xs = input.trim().split('\n');
   let N = xs[0].trim().split('');
   let A = xs[1].trim().split('');
   let B = xs[2].trim().split('');
   let C = xs[3].trim().split('');
   let count = 0;
   for(let i=0; i<N; i++){
     if(A[i]==B[i]&&B[i]==C[i]){
     count +=0;
     }else if(A[i]==B[i]||A[i]==C[i]||B[i]==C[i]){
     count +=1;
     }else{
     count +=2;
     }
   }
   console.log(count);

}
Main(require('fs').readFileSync('/dev/stdin','utf8'));