#![allow(non_snake_case, unused_must_use, unused_imports)]
use std::io::{self, prelude::*};

fn main() {
    let (stdin, stdout) = (io::read_to_string(io::stdin()).unwrap(), io::stdout());
    let (mut stdin, mut buffer) = (stdin.split_whitespace(), io::BufWriter::new(stdout.lock()));

    macro_rules! input {
        ($t: tt, $n: expr) => {
            (0..$n).map(|_| input!($t)).collect::<Vec<_>>()
        };
        (Chars) => {
            input!(String).chars().collect::<Vec<_>>()
        };
        (Usize1) => {
            stdin.next().unwrap().parse::<usize>().unwrap() - 1
        };
        ($t: ty) => {
            stdin.next().unwrap().parse::<$t>().unwrap()
        };
    }

    let N = input!(usize);
    let W = input!(usize, N);

    let mut dp = vec![false; 100 * 100 + 1];
    dp[0] = true;

    let S = W.iter().sum::<usize>();

    for w in W {
        for i in (0..=100 * 100).rev() {
            if dp[i] {
                dp[i + w] = true;
            }
        }
    }

    if S % 2 == 0 && dp[S / 2] {
        writeln!(buffer, "possible");
    } else {
        writeln!(buffer, "impossible");
    }
}