#include <algorithm>
#include <iostream>
#include <iomanip>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <cmath>
using namespace std;

#define FOR(i,s,e) for (int i = int(s); i != int(e); i++)
#define FORIT(i,c) for (typeof((c).begin()) i = (c).begin(); i != (c).end(); i++)
#define ISEQ(c) (c).begin(), (c).end()

int main(){
	int N;
	cin >> N;
	int W[N+1];
	int sum = 0;
	FOR(i,0,N) {
		cin >> W[i+1];
		sum += W[i+1];
	}
	if (sum % 2 != 0){
		cout << "impossible" << endl;
		return 0;
	}else{
		sum = sum/2;
	}

	bool dp[101][5010] = {0};

	FOR(i,0,N+1){
		FOR(j,0,5002){
			if(i == 0 && j == 0) dp[i][j] = true;
			else if(i > 0 && j < W[i]) dp[i][j] = dp[i-1][j];
			else if(i > 0 && j >= W[i]) dp[i][j] = dp[i-1][j] + dp[i-1][j-W[i]];
			else dp[i][j] = false;
		}
	}

	string ans = "";
	if (dp[N][sum]) ans = "possible";
	else ans = "impossible";

	cout << ans << endl;
	return 0;
}