#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <map>
#include <set>
#include <list>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <iomanip>

#define ll long long
#define SIZE 10001

using namespace std;

int N;
int W[SIZE];
int S = 0;

bool dfs(int i, int sum)
{
	if (S % 2 == 1) return false;
	if (i == N) return (S / 2 == sum);

	if (dfs(i + 1, sum)) return true;
	if (dfs(i + 1, sum + W[i])) return true;

	return false;

}

int main()
{

	cin >> N;

	for (int i = 0; i < N; i++) {
		cin >> W[i];
		S += W[i];
	}
	if (dfs(0, 0)) cout << "possible" << endl;
	else           cout << "impossible" << endl;

}