use proconio::*;
fn main(){
    input!{n:usize,w:[usize;n]}
    let wt=w.iter().sum::<usize>();
    if wt%2!=0{
        println!("impossible");
    }else{

        let mut dp=vec![vec![false;wt+1];n+1];
        dp[0][0]=true;
        for i in 1..=n{
            for j in 0..=wt{
                dp[i][j]=dp[i-1][j];
                if j>=w[i-1]{
                    dp[i][j]=dp[i][j]||dp[i-1][j-w[i-1]];
                }
            }
        }
        println!("{}",if dp[n-1][wt/2] {"possible"} else {"impossible"});
    }
}