import std.algorithm, std.array, std.container, std.range;
import std.string, std.conv, std.math;
import std.stdio, std.typecons;

void main()
{
  auto n = readln.chomp.to!int;
  auto wi = readln.split.map!(to!int).array;

  writeln(calc(n, wi) ? "possible" : "impossible");
}

bool calc(int n, int[] wi)
{
  auto sum = reduce!("a + b")(0, wi);

  if (sum % 2 == 1)
    return false;

  auto m = sum / 2;

  auto dp = new bool[m + 1];
  dp[0] = true;

  foreach (w; wi) {
    for (auto i = m; i >= w; --i) {
      dp[i] = dp[i] || dp[i - w];
    }
  }

  return dp[m];
}