#[allow(dead_code)]
fn getline() -> String
{
	let mut inp: String = String::new();
	match std::io::stdin().read_line(&mut inp) {
		Ok(_) => inp.trim().to_string(),
		Err(e) => format!("{}",e),
	}
}

#[allow(dead_code)]
fn depth_search(flag: &Vec<bool>, weight: &Vec<i32>, depth: i32) -> bool
{
	if depth as usize == weight.len() {
		let mut lftsum = 0;
		let mut rhtsum = 0;
		for i in 0..depth as usize {
			if flag[i] == true {
				lftsum += weight[i];
			}
			else {
				rhtsum += weight[i];
			}
		}
		if lftsum == rhtsum {
			return true;
		}
		else {
			return false;
		}
	}

	let mut nxtflag: Vec<bool> = vec![false; weight.len() as usize];

	// Left Search
	nxtflag.copy_from_slice(&flag);
	if depth_search(&nxtflag, &weight, depth+1) == true {
		return true;
	}

	// Right Search

	nxtflag[depth as usize] = true;
	if depth_search(&nxtflag, &weight, depth+1) == true {
		return true;
	}
	
	false
}

fn main()
{
	let mut inp = getline();
	let mut weight: Vec<i32> = Vec::new();
	let n: i32 = inp.parse().unwrap();
	let flag: Vec<bool> = vec![false; n as usize];
	
	inp = getline();
	let tmp: Vec<_> = inp.split(" ").collect();
	for x in tmp {
		weight.push(x.parse().unwrap());
	}
	if depth_search(&flag, &weight, 0) == true {
		println!("possible");
	}
	else {
		println!("impossible");
	}
}