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)

// inputに入力データ全体が入る
function Main(input) {
    input = input.split("\n");
    N = parseInt(input[0]);
    answer = 0;
    moto_word = [];
    for(i = 0; i < N; i++){
        words = {};
        words_array = [];
        for(j = 1; j < input.length; j++){
            are = input[j].split("");
            i_word = are[i];
            if(words[i_word] === undefined) words[i_word] = 1;
            else words[i_word] = words[i_word] + 1;
            words_array.push(i_word);
        }
        kousi = {
            word: undefined,
            number: 0
        }
        for(k = 0; k < N; k++){
            if(words[words_array[k]] > kousi.number){
                kousi.word = words_array[k];
                kousi.number = words[words_array[k]];
            }
        }
        moto_word.push(kousi.word);
    }
    for(j = 1; j < input.length; j++){
        if(i === j) continue;
        hikaku_word = input[j].split("");
        for(k = 0; k < N; k++){
            if(moto_word[k] !== hikaku_word[k]) answer++
        }
    }
    console.log('%d',answer);
}
//*この行以降は編集しないでください（標準入出力から一度に読み込み、Mainを呼び出します）
Main(require("fs").readFileSync("/dev/stdin", "utf8"));