use std::io::*;
use std::str::FromStr;
use utils::*;

pub fn main() {
    let i = stdin();
    let mut o = Vec::new();
    run(i.lock(), &mut o);
    stdout().write_all(&o).unwrap();
}

fn run<R: BufRead, W: Write>(i: R, o: &mut W) {
    let mut i = CpReader::new(i);
    let n = i.read::<usize>();
    let w = i.read_vec::<usize>(n);
    let r = if solve(&w) { "possible" } else { "impossible" };
    writeln!(o, "{}", r).unwrap();
}
fn solve(w: &[usize]) -> bool {
    let sum: usize = w.iter().sum();
    if sum % 2 == 1 {
        return false;
    }
    let t = sum / 2;
    let mut b = vec![false; t];
    b[0] = true;
    for &w in w {
        for i in (0..b.len()).rev() {
            if b[i] {
                let next = i + w;
                if next == t {
                    return true;
                }
                if next < t {
                    b[next] = true;
                }
            }
        }
    }
    false
}

mod utils {
    use super::*;

    pub struct CpReader<R: BufRead> {
        r: R,
        s: String,
    }

    impl<R: BufRead> CpReader<R> {
        pub fn new(r: R) -> Self {
            CpReader {
                r: r,
                s: String::new(),
            }
        }
        pub fn read_line(&mut self) -> &str {
            self.s.clear();
            self.r.read_line(&mut self.s).unwrap();
            self.s.trim()
        }

        pub fn read<T: FromStr>(&mut self) -> T {
            self.read_line().parse().ok().unwrap()
        }

        pub fn read_vec<T: FromStr>(&mut self, n: usize) -> Vec<T> {
            self.read_line()
                .split(' ')
                .take(n)
                .map(|x| x.parse().ok().unwrap())
                .collect()
        }
    }
}