#include <iostream>
#include <stdio.h>
#include <cstring>
#include <math.h>
#include <algorithm>
#include <vector>
#include <string>
#include <stdlib.h>
#include <queue>
#include <utility>
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define ll long long
#define LL long long
#define INF 100000000
using namespace std;
int keta(int n,int k){return (n/int(pow(10,double(k-1)))) % 10;} //nの下からk桁目


int main(){
	
	int n;
	cin>>n;
	int *w;
	w=new int[n];
	int sw=0;
	rep(i,n){
		cin>>w[i];
		sw+=w[i];
	}
	if(sw%2==1){
		cout<<"impossible"<<endl;
		return 0;
	}
	sw/=2;
	
	vector<vector<int>> dp;
	dp.resize(n);
	rep(i,n){
		dp[i].resize(sw+1);
	}
	rep(j,sw+1){
		if(j==w[0]){
			dp[0][j]=1;
		}else{
			dp[0][j]=0;
		}
	}
	dp[0][0]=1;
	FOR(i,1,n){

		rep(j,sw+1){
			if(j==0){
				dp[i][j]=1;
			}
			if(j-w[i]<0){
				dp[i][j]=dp[i-1][j];
			}else{
				dp[i][j]=max(dp[i-1][j],dp[i-1][j-w[i]]);
			}
		}
	}

	/*rep(j,sw+1){
		cout<<j<<" ";
		rep(i,n){
			cout<<dp[i][j]<<" ";
		}
		cout<<endl;
	}*/

	if(dp[n-1][sw])cout<<"possible"<<endl;
	else cout<<"impossible"<<endl;

	delete[]w;
	return 0;
	
}