<?php
$n = trim(fgets(STDIN));
$weights = explode(" ", trim(fgets(STDIN)));
$sum = array_sum($weights);
$dp = array_fill(0, $n, array_fill(0, $sum + 1, false));
$dp[0][$weights[0]] = true;
for ($i = 1; $i < $n; $i++) {
	$w = $weights[$i];
	for ($j = 0; $j <= $sum; $j++) {
		if (!$dp[$i - 1][$j]) continue;
		if ($j + $w <= $sum) $dp[$i][$j + $w] = true;
		if ($j - $w >= 0)    $dp[$i][$j - $w] = true;
		if ($w - $j >= 0)    $dp[$i][$w - $j] = true;
	}
}
echo $dp[$n - 1][0] ? "possible" : "impossible";
?>