#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <queue>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>

using namespace std;

inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

const double EPS = 1e-10;
const double PI  = acos(-1.0);

#define CLR(a) memset((a), 0 ,sizeof(a))

#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int N;
	cin >> N;
	vector<int> W(N);
	int total = 0;
	REP(i, N){
		cin >> W[i];
		total += W[i];
	}

	vector<vector<bool> > dp(N + 1, vector<bool>(total + 1, false));
	REP(i, N + 1) dp[i][0] = true;
	int num = 0;
	REP(i, N){
		num += W[i];
		REP(j, num + 1){
			if(dp[i][j] == true){
				dp[i + 1][j] = true;
				dp[i + 1][j + W[i]] = true;
			}
		}
	}

	if(total % 2 == 1) cout << "impossible" << endl;
	else if(dp[N][total / 2] == true) cout << "possible" << endl;
	else cout << "impossible" << endl;

	return 0;
}