#include <cstdio>
#include <iostream>
#include <algorithm>
#include <complex>
#include <queue>
#include <map>
#include <string>
using namespace std;

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define pb push_back
#define ALL(a) (a).begin(),(a).end()

#define PI 3.1415926535

typedef long long ll;
typedef pair<int, int> P;
//typedef complex<double> C;

const int MAX_N = 100;
const int CENTER = 6000;			// 0の位置
const int WIDTH = 2 * CENTER + 1;	// +と-の方向に広がる

int N;
int w[MAX_N];
bool dp[MAX_N + 1][WIDTH];

void input() {
	cin >> N;
	REP(i, N) cin >> w[i];
}

void solve() {
	REP(i, N + 1) REP(j, WIDTH) dp[i][j] = false;
	dp[0][CENTER] = true;

	REP(i, N) {
		REP(j, WIDTH) {
			if(dp[i][j]) {
				dp[i + 1][j - w[i]] = dp[i + 1][j + w[i]] = true;
			}
		}
	}

	if (dp[N][CENTER]) {
		cout << "possible" << endl;
	} else {
		cout << "impossible" << endl;
	}
}

int main() {
	input();
	solve();
}