package yukicoder;

import java.util.ArrayList;
import java.util.Scanner;

public class N4 {
	private int n, sum, half;
	private int[] bobs;
	private boolean[][] dp;
	
	public static void main(String[] args){
		N4 n4 = new N4();
	}

	N4(){
		Scanner sc = new Scanner(System.in);
		this.n = sc.nextInt();
		this.bobs = new int[n];
		this.dp = new boolean[n + 1][10000];
		
		for(int i = 0;i < n;++i){
			bobs[i] = sc.nextInt();
			sum += bobs[i];
		}
		
		if(sum % 2 == 1){
			System.out.println("impossible");
			return;
		}
		
		this.half = sum / 2;
		
		if(this.solve()){
			System.out.println("possible");
		}else{
			System.out.println("impossible");
		}
	}
	
	//めう
	private boolean solve() {
		dp[0][0] = true;
		for(int k = 0;k < n;++k){
			int b = bobs[k];
			for(int weight = 0;weight < 10000;++weight){
				if(dp[k][weight]){
					dp[k + 1][weight + b] = true;
					dp[k + 1][weight] = true;
				}
			}
		}
		
		return dp[this.n - 1][half];
	}
}