#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 dfs(int i,int x,int *w){
	if(x==0) return 1;
	if(x<0) return 0;
	if(i<0) return 0;
	return max(dfs(i-1,x,w),dfs(i-1,x-w[i],w));
}

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;
	if(dfs(n-1,sw,w)) cout<<"possible"<<endl;
	else cout<<"impossible"<<endl;



	delete[]w;
	return 0;
	
}