#!/usr/local/bin/perl

$string1 = <STDIN>;
chop ($string1);
$len1 = length ($string1);
$string2 = <STDIN>;
chop ($string2);
$len2 = length ($string2);
if ($len1 % 8 != 0) {
        $string1 = "0" x (8 - $len1 % 8) . $string1;
        $len1 += 8 - $len1 % 8;
}
if ($len2 % 8 != 0) {
        $string2 = "0" x (8 - $len2 % 8) . $string2;
        $len2 += 8 - $len2 % 8;
}
if ($len1 > $len2) {
        $string2 = "0" x ($len1 - $len2) . $string2;
} else {
        $string1 = "0" x ($len2 - $len1) . $string1;
        $len1 += ($len2 - $len1);
}
$bytes1 = pack ("h*", $string1);
$bytes2 = pack ("h*", $string2);
$carry = 0;
$count = $len1 - 1;
while ($count >= 0) {
        $nybble1 = vec ($bytes1, $count, 4);
        $nybble2 = vec ($bytes2, $count, 4);
        $result = ($nybble1 + $nybble2 + $carry) & 15;
        $carry = ($nybble1 + $nybble2 + $carry) >> 4;
        vec ($bytes1, $count, 4) = $result;
        $count--;
}
$resultstring = unpack ("h*", $bytes1);
$resultstring = $carry . $resultstring if ($carry > 0);
print ("$resultstring\n");
