#include <iostream>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cmath>
#define N_MAX 100
using namespace std;

int N, W[N_MAX];

bool cal(int n, int s)
{
	if (s == 0)
		return true;
	if (s < 0 || n >= N)
		return false;

	s -= W[n];
	for (int i = n + 1; i < N; ++i)
		if (cal(n + i, s))
			return true;
	return false;
}

bool cal(int s)
{
	if (s & 1)
		return false;

	s /= 2;

	for (int i = 0; i < N; ++i)
		if (cal(i, s))
			return true;
	return false;
}

int main()
{
	int sum = 0;

	cin >> N;
	for (int i = 0; i < N; ++i)
	{
		cin >> W[i];
		sum += W[i];
	}

	if (cal(sum))
		cout << "possible";
	else
		cout << "impossible";

	return 0;
}