/*
 * douteki.c
 *
 *  Created on: 2016/09/13
 *      Author: admin
 */


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int main(){
	char str[10000];
	char *tmp;
	int n=0, i=0, j=0;
	int sum_w=0, half=0;
	int w[100] = {0};
	int check[10001] = {0};

	check[0] = 1;

	fgets(str, sizeof(str), stdin);
	n = atoi(str);

	printf("%d\n", n);

	fgets(str, sizeof(str), stdin);

	tmp = strtok(str, " ");
	w[0] = atoi(tmp);
	sum_w = w[0];

	for(i = 1; i < n; i++){
		tmp = strtok(NULL, " ");
		w[i] = atoi(tmp);
		sum_w += w[i];
	}

	half = sum_w / 2;
	printf("%d %d\n", sum_w, half);

	if(half % 2 == 1){
		printf("impossible\n");
		goto end;
	}

	for(i = 0; i < n; i++){
		for(j = sum_w; j >= 0; j--){
			if(check[j] == 1){
				check[w[i] + j] = 1;
			}
		}
	}

	if(check[half] == 1){
		printf("possible\n");
	}
	else{
		printf("impossible\n");
	}

end:
	return 0;
}