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

    // calc
    let mut dp: Vec<bool> = vec![false; 10010];
    let total: usize = a.iter().sum();
    dp[0] = true;
    for i in 0..n {
        for j in (a[i]..10001).rev() {
            dp[j] |= dp[j - a[i]];
            if dp[j] && dp[total - j] && j * 2 == total {
                println!("possible");
                return;
            }
        }
    }
    println!("impossible");
}