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

int n, w[101];
int total = 0;

int dfs(int i, int sum)
{
	if(sum * 2 == total){
		printf("possible\n");
		exit(0);
	}
	if(i >= n || sum * 2 > total){
		return 0;
	}
	dfs(i + 1, sum);
	dfs(i + 1, sum + w[i]);
}

int main(void) {
	int i;
	
	scanf("%d", &n);
	for(i = 0;i < n;i++){
		scanf("%d", &w[i]);
		total += w[i];
	}
	dfs(1, w[0]);
	printf("impossible\n");
	return 0;
}