import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int [] W = new int [N];
        int TW = 0;
        for(int i=0; i<N; i++){
            W[i] = sc.nextInt();
            TW = TW + W[i];
        }
        if(TW%2==1){
            System.out.println("impossible");
            return;
        }
        int HW = TW/2;
        boolean [][] PW = new boolean [N+2][TW];
        PW[0][W[0]-1]=true;
        for(int i=1; i<N; i++){
            for(int j=0; j<HW; j++){
                if(PW[i-1][HW-1-j]==true){
                    PW[i][HW-1-j+W[i]]=true;
                    PW[i][HW-1-j]=true;
                }
                if(PW[i][HW-1]==true){
                    System.out.println("possible");
                    return;
                }
            }
        }
        System.out.println("impossible");
    }
}