#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())
#define indexOf(v,x) (find(all(v),x)-v.begin())



int main(){
	bool dp[5101]={};
	int n,s=0;
	cin>>n;
	dp[0]=true;
	rep(i,n){
		int w;
		cin>>w;
		s+=w;
		for(int j=5000;j>=0;j--){
			dp[w+j]|=dp[j];
		}
	}
	cout<<(s%2==0&&dp[s/2]?"possible":"impossible")<<endl;
	return 0;
}