#include <stdio.h>

int n, i, ans, a[100];

int solve(int i, int m)
{
	if(m==0) return 1;
	if(i>=n) return 0;
	int res=solve(i+1, m)||solve(i+1, m-a[i]);
	return res;
}

int main(void)
{
	scanf("%d", &n);

	for(i=0; i<n; i++)
	{
		scanf("%d", &a[i]);
		ans+=a[i];
	}

	if(solve(0, ans/2)&&ans%2==0) printf("possible\n");
	else printf("impossible\n");

	return 0;
}