import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Main {
	public static void main(String[] args) {
	      BufferedReader stdReader =new BufferedReader(new InputStreamReader(System.in));
	      try {
		      int N = Integer.parseInt(stdReader.readLine());
		      String[] temps = stdReader.readLine().split(" ");
		      int[] nums = new int[N+1];
		      int sum = 0;
		      for(int i=0;i<N;i++){
		    	  nums[i+1] = Integer.parseInt(temps[i]);
		    	  sum += nums[i+1];
		      }
		      if(sum%2 != 0){
		    	  System.out.println("impossible");
		    	  return;
		      }
		      Arrays.sort(nums);
		      int half = sum/2;
		      boolean[] dp = new boolean[half+1];
		      dp[nums[1]] =  true;
		      for(int i=2;i<nums.length;i++){
		    	  dp[nums[i]] = true;
		    	  for(int j=1;j<half+1;j++){
		    		  if(j > nums[i]) break;
		    		  if(dp[j] && j+nums[i] <= half) dp[j+nums[i]] = true;
		    	  }
		      }
		      if(dp[half]) System.out.println("possible");
		      else System.out.println("impossible");
	    	  } catch (IOException e) {
			e.printStackTrace();
	      }
	}	
}