Submission #2105565

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Source Code Expand

<?php
$s = trim(fgets(STDIN));
$max = $paren = 0;
for ($i = 0; $i < strlen($s); $i++) {
    if ($s[$i] === '2') $paren++; else $paren--;
    $max = max($max, $paren);
    if ($paren < 0) {
        print "-1\n"; exit;
    }
}
if ($paren !== 0) {
    print "-1\n";
} else {
    print "{$max}\n";
}

Submission Info

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