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");
	var n = parseInt(input[0], 10);
	var a = input[1].split("");
	var b = input[2].split("");
	var c = input[3].split("");
	var abCount = 0;
	var acCount = 0;
	var bcCount = 0;
	for (  var i = 0;  i < n;  i++  ) {
		if ((a[i] != b[i])) {
			abCount++;
		};
		if ((a[i] != c[i])) {
			acCount++;
		};
		if ((b[i] != c[i])) {
			bcCount++;
		};
	};
	var aCount = abCount + acCount;
	var bCount = abCount + bcCount;
	var cCount = acCount + bcCount;
        //出力
	console.log('%d',Math.min(aCount, bCount, cCount));
}
//*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"));