<?php
// Here your code !
$count = trim(fgets(STDIN));
$weights = explode(' ', trim(fgets(STDIN)));
$sum = array_sum($weights);
if ($sum % 2 == 1) {
    echo 'impossible';
    exit;
}

$point = array_fill(0, $sum + 1, false);
$point[0] = true;

foreach ($weights as $weight) {
    for ($i = $sum; $i >= 0; $i--) {
        if ($point[$i]) {
            $point[$i + $weight] = true;
        }
    }
}
echo ($point[$sum / 2]) ? 'possible' : 'impossible';