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)

function Main(input){
    		var input = input.split(/\r\n|\r|\n/);
        	var n = parseInt(input[0],10);
        	var a = input[1].split("");
        	var b = input[2].split("");
        	var c = input[3].split("");
        	var point = new Array(3);
        	point[0] = 0;
        	point[1] = 0;
        	point[2] = 0;
        	var cnt = 0;
        	while (cnt < n) {
        		if (a[cnt] == b[cnt]){
        			point[0]++;
        		}
        		cnt++; 
    		}
    		var cnt = 0;
    		while (cnt < n) {
        		if (a[cnt] == c[cnt]){
        			point[1]++;
        		}
        		cnt++; 
    		}
    		var cnt = 0;
    		while (cnt < n) {
        		if (b[cnt] == c[cnt]){
        			point[2]++;
        		}
        		cnt++; 
    		}
    		point.sort();
    		ans = (5-point[1])+(5-point[2]);
    		    	console.log('%d %s',ans);
    		}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));