Problem:
Score : 200 points

Problem Statement

Given are strings S and T. Consider changing S to T by repeating the operation below. Find the minimum number of operations required to do so.

Operation: Choose one character of S and replace it with a different character.

Constraints

S and T have lengths between 1 and 2\times 10^5 (inclusive).

S and T consists of lowercase English letters.

S and T have equal lengths.

Input

Input is given from Standard Input in the following format:

S
T

Output

Print the answer.

Sample Input 1

cupofcoffee
cupofhottea

Sample Output 1

4

We can achieve the objective in four operations, such as the following:

First, replace the sixth character c with h.

Second, replace the eighth character f with t.

Third, replace the ninth character f with t.

Fourth, replace the eleventh character e with a.

Sample Input 2

abcde
bcdea

Sample Output 2

5

Sample Input 3

apple
apple

Sample Output 3

0

No operations may be needed to achieve the objective.

Solution in PHP (7.4.4) (judge verdict: Wrong Answer)

<?php
$input1 = fgets(STDIN);
$input2 = fgets(STDIN);
$array1 = str_split($input1);
$array2 = str_split($input2);

if ($input1 == $input2) {
   echo 0;
} else {
    $num = 0;
    for ($i = 0; $i < count($array1); $i++) {
        if ($array1[$i] != $array2[$i]) {
            $num ++;
        }
    }
    echo $num -  1;
}