#include<iostream>
#include<algorithm>
#define INF (1<<30)
using namespace std;

//yuki 4 おもりと天秤

int n,w[101],ms,dp[10001];

int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>w[i];
		ms+=w[i];
	}
	if(ms%2==1){
		cout<<"impossible"<<endl;
	}
	else{
		ms/=2;
		dp[0]=1;
		for(int i=1;i<=n;i++){
			dp[w[i]]=1;
			for(int j=1;j<=10000;j++){
				if(dp[j]==1) dp[j+w[i]]=1;
			}
		}
		if(dp[ms]==1) cout<<"possible"<<endl;
		else cout<<"impossible"<<endl;
	}
	return 0;
}