<?php
$n = trim(fgets(STDIN));
$w_array = explode(" ",trim(fgets(STDIN)));

// 合計値が偶数でないなら組み合わせはないので即終了
$w_total = array_sum($w_array);
if ( $w_total % 2 ) {
	echo 'impossible'.PHP_EOL;
	return 0;
}

$dp = array(0=>TRUE);
for ( $i = 0; $i < count($w_array); $i++ ) {
	foreach ( $dp as $weight => $value ) {
		if ( $value === TRUE ) {
			$dp[$weight+$w_array[$i]] = TRUE;
		}
	}
}

$w_target = $w_total / 2;

if ( isset($dp[$w_target]) && ($dp[$w_target] === TRUE) ) {
	echo 'possible'.PHP_EOL;
}
else {
	echo 'impossible'.PHP_EOL;
}