import java.util.*;

public class Exercise44{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    int[] weight = new int[n];
    int sum = 0;

    for (int i = 0; i < n; i++){
      int x = sc.nextInt();
      weight[i] = x;
      sum += x;
    }

    if(sum % 2 == 1){
      System.out.println("impossible");
      System.exit(0);
    }

    int[][] dp = new int[n + 1][sum + 1];

    for(int i = 0; i < n + 1; i++){
      for (int j = 1; j < sum + 1; j++){
        dp[i][j] = -1;
      }
    }

    for(int a = 0; a < n; a++){
      for(int b = 0; b < sum; b++){
        if(dp[a][b] >= 0){
          dp[a + 1][b] = dp[a][b];
          dp[a + 1][b + weight[a]] = dp[a][b] + weight[a];
        }
      }
    }

    if (dp[n][sum / 2] >= 0){
      System.out.println("possible");
	   }else{
       System.out.println("impossible");
     }
  }
}