#include<stdio.h>

int n;
int w[101],dp[101][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][rw] != -1) return dp[i][rw];

	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][rw] = res;
	return res;
}

int main(void){
	int j,k,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<101;j++)
		for(k=0;k<101;k++)
			dp[j][k] = -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;
}