#include<stdio.h>

int n;
int w[101],dp[101];

int Max(int i,int j){
	return i>j ? i:j;
}

/*i以降でrwを超えない最大のwを返す関数*/
int solver(int i,int rw){
	if(dp[i] != -1) return dp[i];
	else{
		int res;
		if(i==n) res=0;
		else if(w[i]>rw){
			res = solver(i+1,rw);
		}
		else{
			res = Max(solver(i+1,rw),solver(i+1,rw-w[i])+w[i]);
		}

		dp[i] = res;
		return res;
	}
}

int main(void){
	int j,sum=0;
	scanf("%d",&n);

	for(j=0;j<n;j++)
		scanf("%d",&w[j]);

	for(j=0;j<n;j++)
		sum += w[j];

	for(j=0;j<n;j++)
		dp[j] = -1;

	if(sum%2 != 0) printf("impossible\n");
	else if(solver(0,sum/2) == sum/2) printf("possible\n");
	else  printf("impossible\n");

	return 0;
}