#include<iostream>
#include<algorithm>
using namespace std;
using lint=int64_t;

int main()
{
	int N;
	int W[110];
	int sum=0;

	cin >> N;
	for(int i=1;i<=N;i++)
	{
		cin >> W[i];
		sum+=W[i];
	}

	if(sum%2==1)
	{
		cout << "impossible" << endl;
		return 0;
	}

	sum/=2;
	bool dp[10010]={true};
	for(int i=1;i<=N;i++)
		for(int j=sum;j>=0;j--)
			if(j-W[i]>=0)
				dp[j]|=dp[j-W[i]];

	if(dp[sum])
		cout << "possible";
	else
		cout << "impossible";
	cout << endl;
	return 0;
}