use std::io;
use std::io::prelude::*;
use std::io::BufReader;

fn calc(args: &Vec<String>) -> bool {
    //let n: u32 = args[0].parse().unwrap();
    let ws: Vec<u32> = args[1].split(' ').map(|s| s.parse().unwrap()).collect();

    let s = ws.iter().fold(0, |a, b| a + b);
    let t = s / 2;

    if s % 2 == 1 {
        return false;
    }

    let mut memo = vec![false; (t + 1) as usize];
    memo[0] = true;

    for w in ws {
        for i in (0..(t + 1) as usize).rev() {
            if i >= w as usize {
                memo[i] = memo[i] || memo[i - w as usize];
            }
        }
    }

    memo[t as usize]
}

fn run(args: &Vec<String>) -> Vec<String> {
    if calc(args) {
        vec!["possible".to_string()]
    } else {
        vec!["impossible".to_string()]
    }
}

fn main() {
    let args = lines(BufReader::new(io::stdin()));
    for line in run(&args) {
        println!("{}", line);
    }
}

fn lines<R: Read>(reader: BufReader<R>) -> Vec<String> {
    reader.lines().map(|l| l.unwrap()).collect()
}