#include <iostream>
#include <cstring>
using namespace std;

#define N 100

int n;
int w[N];
int hw;

int dfs(int no, int tw)
{
	tw += w[no];
	if ( tw == hw ) {
		return 1;
	}
	if ( tw > hw ) {
		return -1;
	}
	for ( int i = no + 1; i < n; i++ ) {
		int x = dfs(i, tw);
		if ( x == 1 ) {
			return x;
		}
	}
	return 0;
}

int main()
{
	cin >> n;
	for ( int i = 0; i < n; i++ ) {
		cin >> w[i];
		hw += w[i];
	}
	if ( hw % 2 == 0 && (hw /= 2, dfs(0, 0) == 1) ) {
		cout << "possible" << endl;
	}
	else {
		cout << "impossible" << endl;
	}

	return 0;
}