fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut w = String::new();
    std::io::stdin().read_line(&mut w).ok();
    let w: Vec<usize> = w.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let summary = w.iter().sum::<usize>();
    if summary % 2 == 1 {
        println!("impossible");
        return;
    }
    let limit = summary/2;
    let mut dp = vec![vec![false; limit+1]; n+1];
    dp[0][0] = true;
    for i in 0..n {
        for j in 0..=limit {
            dp[i+1][j] |= dp[i][j];
            if j+w[i]<=limit {
                dp[i+1][j+w[i]] |= dp[i][j];
            }
        }
    }
    if dp[n][limit] {
        println!("possible");
    } else {
        println!("impossible");
    }
}