#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<vector>
#include<queue>
#include<set>
#include<map>
#include<utility>
#include<sstream>
#include<cctype>
#include<cmath>
#include<algorithm>
using namespace std;

#define ALL(x) (x).begin(),(x).end()
#define RALL(x) (x).rbegin(), (x).rend()
#define rev(i,n) for(int (i)=(n-1);(i)>=0;(i)--)
#define repp(i,n) for(int (i)=1;(i)<=(n);(i)++)
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define rev(i,n) for(int (i)=(n-1);(i)>=0;(i)--)
#define clr(a) memset((a), 0 ,sizeof(a))


typedef pair<int,int> P;
typedef vector<pair<int,string> > pii;
typedef map<string,int> mi;


vector<int>vc;
int A[1000];
bool memo[10000];
int n,sum;

void dfs(int a,int b){
	if(a==n)return;
	memo[b]=true;
	dfs(a+1,b);
	dfs(a+1,A[a]+b);
}

int main(){
	cin >> n;
	for(int i=0;i<n;i++){
		cin >> A[i];
		sum+=A[i];
	}
	dfs(0,0);
	cout << (sum%2==0&&memo[sum/2]?"possible":"impossible") << endl;
	return 0;
}