<?php
$N = (int)trim(fgets(STDIN));
$w = array_map('intval', explode(' ', trim(fgets(STDIN))));
$dp = [];
$sum = array_sum($w);

if ($sum % 2 === 1) {
  echo "impossible\n";
  exit;
}

for ($i = $N; $i >= 0; $i--) {
  for ($j = 10000; $j >= 0; $j--) {
    if ($i === $N) {
      $dp[$i][$j] = false;
      continue;
    }
    if ($j === (int)($sum / 2)) {
      $dp[$i][$j] = true;
      continue;
    }
    $a = isset($dp[$i + 1][$j + $w[$i]]) ? $dp[$i + 1][$j + $w[$i]] : false;
    $b = isset($dp[$i + 1][$j]) ? $dp[$i + 1][$j] : false;
    $dp[$i][$j] =  $a || $b;
  }
}

echo $dp[0][0] ? "possible\n" : "impossible\n";