#include <iostream>
#include <sstream>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <vector>
#include <array>
#include <list>
#include <map>
#include <bitset>
#include <memory>
#include <algorithm>
#include <utility>
#include <numeric>

namespace Util
{

std::vector<std::string> Split(const std::string& str, const char delim);
std::string Itos(const int value);
std::string Ftos(const double value);
int Stoi(const std::string& buf);
double Stof(const std::string& buf);
std::vector<int> ConvertInt(const std::vector<std::string>& buffers);
std::vector<double> ConvertDouble(const std::vector<std::string>& buffers);

}// namespace Util


int main()
{
	// 入出力の速度向上
	std::cin.tie(0);
	std::ios::sync_with_stdio(false);

	std::string buf;
	std::vector<std::string> buffers;

	std::vector<int> weight;
	std::vector<int> dp;
	int sum;

	std::getline(std::cin, buf);
	std::getline(std::cin, buf);
	weight = std::move(Util::ConvertInt(Util::Split(buf, ' ')));

	dp.resize(10000 + 10, 0);
	dp[0] = 1;
	sum = 0;

	for(int item = 0; item < static_cast<int>(weight.size()); ++item)
	{
		sum += weight[item];

		for(int cur = static_cast<int>(dp.size()) - 1; 0 <= cur; --cur)
		{
			if(dp[cur] == 1)
			{
				if(cur + weight[item] < static_cast<int>(dp.size()))
				{
					dp[ cur + weight[item] ] = 1;
				}
			}
		}
	}

	printf("%s\n", (dp[ sum / 2] == 1 && sum % 2 == 0) ? "possible" : "impossible");



	return 0;
}


namespace Util
{

std::vector<std::string> Split(const std::string& str, const char delim)
{
	std::istringstream iss(str);
	std::vector<std::string> ret;
	std::string tmp;

	while(std::getline(iss, tmp, delim))
	{
		ret.push_back(tmp);
	}

	return ret;
}

std::string Itos(const int value)
{
	std::ostringstream ostream;
	ostream << value;
	return ostream.str();
}

std::string Itof(const double value)
{
	std::ostringstream ostream;
	ostream << value;
	return ostream.str();
}

int Stoi(const std::string& buf)
{
	return std::atoi(buf.c_str());
}

double Stof(const std::string& buf)
{
	return std::atof(buf.c_str());
}

std::vector<int> ConvertInt(const std::vector<std::string>& buffers)
{
	std::vector<int> ret(buffers.size());

	for(int cur = 0; cur < static_cast<int>(ret.size()); ++cur)
	{
		ret[cur] = Stoi(buffers[cur]);
	}

	return ret;
}

std::vector<double> ConvertDouble(const std::vector<std::string>& buffers)
{
	std::vector<double> ret(buffers.size());

	for(int cur = 0; cur < static_cast<int>(ret.size()); ++cur)
	{
		ret[cur] = Stof(buffers[cur]);
	}

	return ret;
}

}// namespace Util