use std::io::{stdin, Read, StdinLock};
use std::str::FromStr;

struct Input {
    n: usize,
    w: Vec<usize>,
}

fn read_input(cin_lock: &mut StdinLock) -> Input {
    let n = next_token(cin_lock);
    let w = (0..n).map(|_| next_token(cin_lock)).collect();
    Input { n, w }
}

fn solve1(input: Input) -> bool {
    let sum_w = input.w.iter().fold(0, |acc, x| acc + x);
    if sum_w % 2 != 0 {
        return false;
    }

    let half_w = sum_w / 2;
    let mut dp = vec![vec![false; half_w + 1]; input.n + 1];
    dp[0][0] = true;

    for i in 0..input.n {
        let w = input.w[i];
        for j in 0..(half_w + 1) {
            dp[i + 1][j] = dp[i + 1][j] || dp[i][j] || if j < w { false } else { dp[i][j - w] }
        }
    }

    return dp[input.n][half_w];
}

fn solve(input: Input) {
    println!(
        "{}",
        if solve1(input) {
            "possible"
        } else {
            "impossible"
        }
    )
}

fn next_token<T: FromStr>(cin_lock: &mut StdinLock) -> T {
    cin_lock
        .by_ref()
        .bytes()
        .map(|c| c.unwrap() as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect::<String>()
        .parse::<T>()
        .ok()
        .unwrap()
}

fn main() {
    let cin = stdin();
    let mut cin_lock = cin.lock();
    let input = read_input(&mut cin_lock);
    solve(input);
}