<?php
 
$list = [];
while (($line = fgets(STDIN)) !== false) {
    $list[] = rtrim($line, "\r\n");
}
 
$result = [];
 
foreach ($list as $item) {
    $res = IsItsCharsAppearsTwice($item);
    if ($res) {
        $result[] = $res;
    }
}
 
foreach ($result as $word) {
    echo $word, PHP_EOL;
}
 
function IsItsCharsAppearsTwice($word)
{
    $map = [];
    $len = strlen($word);
 
    for ($i = 0; $i < $len; $i++) {
        $char = $word[$i];
        $map[$char] = ($map[$char] ?? 0) + 1;
    }
 
    foreach ($map as $char => $count) {
        if ($count == 2) {
            return $word;
        }
    }
    return null;
}

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

YXNkZgpmZGFzCmFzZHMKZCBmbQpkZmFhCmFhYWEKYWFiYgphYWFiYg==

asdf
fdas
asds
d fm
dfaa
aaaa
aabb
aaabb