#include <stdio.h>

int main(void) {
	int i, j;
	int n, w[101];
	int total = 0;
	int memo[10001] = {0};
 
	scanf("%d", &n);
	for(i = 0;i < n;i++){
		scanf("%d", &w[i]);
		total += w[i];
	}
	if(total % 2 == 1){
		printf("impossible\n");
		return 0;
	}
	for(j = 0;j < n;j++){
		memo[w[j]] = 1;
		for(i = 0;i <= 10000;i++){
			if(memo[w[j]] == 1){
				memo[w[j] * 2] = 1;
			}
			if(memo[i] == 1 && i + w[j] <= 10000){
				memo[i + w[j]] = 1;
			}
		}
	}
	if(memo[total / 2] == 1){
		printf("possible\n");
	}
	else{
		printf("impossible\n");
	}
	return 0;
}