use proconio::input;

fn main() {
    input! {
        n: usize,
        w: [usize; n],
    }
    let sum = w.iter().sum::<usize>();
    if sum % 2 == 1 {
        println!("impossible");
        return;
    }
    let mut dp = vec![0; sum + 1];
    dp[0] = 1;
    for i in 0..n {
        let mut ndp = dp.clone();
        for j in w[i]..=sum {
            ndp[j] |= dp[j - w[i]];
        }
        dp = ndp;
    }
    if dp[sum/2] == 1 {
        println!("possible");
    }else {
        println!("impossible");
    }
}