#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <map>

using namespace std;

#define INF 		2000000007
#define MOD			1000003

#define MAX 		105

#define REP(i,n)	for(int i=0;i<(n);++i)
#define REPS(i,s,t)	for(int i=(s);i<(t);++i)

typedef unsigned int 			uint;
typedef unsigned long long int	ull;


bool DP[105][10010];


int main(){
	int N;cin>>N;

	vector<int> W(N+2);
	REPS(i,1,N+1) cin>>W[i];

	int suml = accumulate(W.begin(),W.end(),0);

	if(suml%2==1){
		cout << "impossible\n";
		return 0;
	}
	suml /= 2;
	REPS(i,1,N+1)DP[i][0]=true;

	for(int i=1;i<=N;++i){
		for(int j=0;j<=suml;++j){
			if(j<W[i])	DP[i][j] |= DP[i-1][j];
			else	DP[i][j] = DP[i-1][j-W[i]] | DP[i-1][j];
		}
	}
	cout << (DP[N][suml] ? "possible\n" : "impossible\n");

	return 0;
}