<?php
$results = [];
 
while (($line = rtrim(fgets(STDIN))) != false) {
    $charList = [];
 
    foreach (str_split($line) as $char) {
        if (isset($charList[$char])) {
            $charList[$char]++;
        } else {
            $charList[$char] = 1;
        }
    }
 
    foreach($charList as $charCount) {
        if ($charCount === 2) {
            $results[] = $line;
            break;
        }
    }
}
 
foreach ($results as $result) {
    echo $result . PHP_EOL;
}
 

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