function main(input) {
  const n = Number(input[0]);
  const w = input[1].split(" ").map(x=>Number(x));
  const b = w.reduce((sum, x) => sum + x);
  if(b % 2 === 1) {
    console.log("impossible");
    return;
  }
  const dp = new Array(b+1).fill(false);
  for(let i=0; i<n; i++) {
    for(let j=b; j>=0; j--) {
      if(dp[j]) dp[j+w[i]] = true;
    }
    dp[w[i]] = true;
  }
  console.log(dp[b/2] ? "possible" : "impossible");
}

main(require("fs").readFileSync("/dev/stdin", "utf8").split("\n"));