#include <iostream>
#include <cmath>
#include <climits>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>
#include <utility>

#define endl '\n'
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

using namespace std;

typedef pair<int,int> P;
typedef long long int LL;

bool dp[100][20000+1];
const int D=10000;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	int N;
	cin>>N;
	std::vector<int> W(N);
	REP(i,N)	cin>>W[i];
	dp[0][D+W[0]]=true;
	dp[0][D-W[0]]=true;
	FOR(i,1,N){
		FOR(j,-10000,10000+1){
			if(0<=j+D+W[i]&&j+D+W[i]<20000+1&&dp[i-1][D+j+W[i]]){
				dp[i][D+j]=true;
			}
			if(0<=j+D-W[i]&&j+D-W[i]<20000+1&&dp[i-1][D+j-W[i]]){
				dp[i][D+j]=true;
			}
		}
	}

/*	REP(i,N){
		FOR(j,-10,11){
			cout<<dp[i][j+D]<<' ';
		}
		cout<<endl;
	}*/

	if(dp[N-1][D]){
		cout<<"possible"<<endl;
	}else{
		cout<<"impossible"<<endl;
	}
	return 0;
}