fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
        .map(|e| e.parse().ok().unwrap()).collect()
}

fn main() {
    let _: usize = read();
    let ws: Vec<usize> = read_vec();
    let w_sum: usize = ws.iter().sum();
    if w_sum % 2 == 1 {
        println!("impossible");
        return;
    }

    let mut dp = vec![false; w_sum / 2 + 1];
    dp[0] = true;
    for i in 0..ws.len() {
        for j in (0..w_sum / 2 + 1).rev() {
            if j >= ws[i] && dp[j - ws[i]] {
                dp[j] = true;
            }
        }
    }
    if dp[w_sum / 2] {
        println!("possible");
    } else {
        println!("impossible");
    }
}