#include<iostream>

using namespace std;

#define NMAX 100
#define WMAX 100
#define DPMAX NMAX*WMAX

int main(){

	int N;
	int W[NMAX];
	int wsum=0;
	int dp[2][DPMAX+1];

	cin>>N;

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

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

	
	for(int i=0;i<N;i++){
		dp[0][0]=1;
		for(int j=0;j<=DPMAX;j++){
			dp[1][j]=0;
		}
		for(int j=0;j<=DPMAX;j++){
			if(dp[0][j]==1){
				dp[1][j+W[i]]=1;
			}
		}
		for(int j=0;j<=DPMAX;j++){
			dp[0][j]=dp[1][j];
		}
	}
	if(dp[0][wsum/2]==1) cout<<"possible"<<endl;
	else cout<<"impossible"<<endl;
}