<?php

$passwords = explode("\n", file_get_contents('input.txt'));

$number_of_good_passwords = 0;

foreach ($passwords as $password) {
    $parts = explode(' ', $password);
    if (count($parts) === 3) {
        [$min, $max] = explode('-', $parts[0]);
        $letter = $parts[1][0];
        $word = $parts[2];
        if ($word[$min-1] === $letter xor $word[$max-1] === $letter) {
            $number_of_good_passwords++;
        }
    }
}

echo $number_of_good_passwords;
exit(0);