use std::collections::{HashMap, HashSet};

use proconio::marker::Chars;

fn main() {
    proconio::input! {
        n: u64,
        w: [u64; n],
    }
    let sum = w.iter().sum::<u64>();
    if sum % 2 == 1 {
        println!("impossible");
        return;
    }
    let half = sum / 2;
    let mut memo = vec![false; half as usize + 1];
    memo[0] = true;
    for w in w {
        for i in (0..half + 1).rev() {
            if memo[i as usize] == false || i + w > half {
                continue;
            }
            memo[(i + w) as usize] = true;
        }
    }
    if memo[half as usize] {
        println!("possible");
    } else {
        println!("impossible");
    }
}

#[cfg(test)]
mod test {
    use super::*;
    #[test]
    fn test() {}
}