#include<stdio.h>
int cmp(const void*a,const void*b){
	return *(int*)a-*(int*)b;
}
int check[5001];

int main(){
	int i,j,n,w[128],s=0;
	scanf("%d",&n);
	for(i=0;i<n;i++){
		scanf("%d",&w[i]);
		s+=w[i];
	}
	qsort(w,n,sizeof(int),cmp);
	if(s%2==0){
		s/=2;
		check[0]=1;
		for(i=0;i<n;i++){
			for(j=0;j+w[i]<=s;j++){
				if(check[j]==1) check[j+w[i]]=1; 
			}
		}
		if(check[s]) printf("possible\n");
		else printf("impossible\n");
	}else printf("impossible\n");
	return 0;
}