#include <bits/stdc++.h>
using namespace std;

int main(){
	int n;cin>>n;
	vector<int> w(n);
	for(int i=0;i<n;i++) cin>>w[i];
	int wsum=0;
	for(int i=0;i<n;i++) wsum+=w[i];
	if(wsum%2){cout<<"impossible\n";return 0;}
	vector<vector<bool>> dp(n+1,vector<bool>(wsum/2+1,false));
	dp[0][0]=true;
	for(int i=0;i<n;i++){
		for(int j=0;j<=wsum/2;j++){
			if(!dp[i][j]) continue;
			dp[i+1][j]=true;
			if(j+w[i]<=wsum/2) dp[i+1][j+w[i]]=true;
		}
	}cout<<(dp[n][wsum/2]?"possible":"impossible")<<"\n";
	return 0;
}