#include<iostream>

using namespace std;

#define NMAX 100
#define WMAX 100
#define WSUM_MAX (NMAX*WMAX)
int main(){

	int N;
	int W[NMAX];
	int sum=0;
	bool dp[WSUM_MAX+1];

	cin>>N;
	for(int i=0;i<N;i++){
		cin>>W[i];
		sum+=W[i];
	}

	if(sum%2==1){
		cout<<"impossible"<<endl;
		return 0;
	}

	for(int i=0;i<=WSUM_MAX;i++){
		dp[i]=false;
	}
	dp[0]=true;

	for(int i=0;i<N;i++){
		for(int j=WSUM_MAX;j>=0;j--){
			if(dp[i]) dp[i+W[i]]=true;
		}
	}

	if(dp[(int)sum/2]) cout<<"possible"<<endl;
	else cout<<"impossible"<<endl;
}