#include <bits/stdc++.h>

using namespace std;

bool dp[5001];

int main() 
{
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	memset(dp,false,sizeof(dp));	
	int n,t;
	vector <int> v;
	int sum = 0;
	cin >> n;
	
	for(int i=0;i<n;i++)
	{
		cin >> t;
		sum += t;
		v.push_back(t);
	}
	
	if(sum%2==1)
	{
		cout << "impossible" << '\n';
		return 0;
	}
	
	dp[0] = true;
	
	for(int i=0;i<n;i++)
	{
		for(int j=(sum/2);j>=0;j--)
		{
			if(dp[j]==false)
			{
				continue;
			}
			if(j + v[i] <= (sum/2))
			{
				dp[j + v[i]] = true;
			}
		}
	}
	
	if(dp[sum/2])
	{
		cout << "possible" << '\n';
	}
	else
	{
		cout << "impossible" << '\n';
	}
	return 0;
}