<?php
set_time_limit (0);

function kumiawase($zentai,$nukitorisu){
    $zentaisu=count($zentai);
    if($zentaisu<$nukitorisu){
        return;
    }elseif($nukitorisu==1){
        for($i=0;$i<$zentaisu;$i++){
            $arrs[$i]=array($zentai[$i]);
        }
    }elseif($nukitorisu>1){
        $j=0;
        for($i=0;$i<$zentaisu-$nukitorisu+1;$i++){
            $ts=kumiawase(array_slice($zentai,$i+1),$nukitorisu-1);
            foreach($ts as $t){
                array_unshift($t,$zentai[$i]);
                $arrs[$j]=$t;
                $j++;
            }
        }
    }
    return $arrs;
}

$count = trim(fgets(STDIN));
$array = explode(" ",trim(fgets(STDIN)));
$sum = array_sum($array);
$sumhanbun = $sum/2;
$flag = 0;


if ($sum%2 != 0){
}else {
    for ($i=1;$i<$count;$i++){
        foreach(kumiawase($array,$i) as $arr){
            $sumkumiawase = array_sum($arr);
            if ($sumkumiawase == $sumhanbun){
                $flag=1;
            }
        }
    }
}

if ($flag == 1) {
    echo 'possible';
}else {
    echo 'impossible';
}