#include <iostream>
#include <vector>
#include <cstdint>

#define GSI 1

typedef std::vector<std::uint64_t> DType;

std::uint64_t Sum(DType& D) {
	std::uint64_t i = 0;
	for (auto& o : D) {
		i += o;
	}
	return i;
}
DType GetInput() {
	std::uint64_t i = 0;
	DType D;

	std::cin >> i;
	while (std::cin >> i) D.push_back(i);

	return D;

}
DType MakeProblem1() {
	DType D{ 1, 2, 3 };
	return D;
}
DType MakeProblem2() {
	DType D{ 1, 2, 3, 4, 5 };
	return D;
}
DType MakeProblem3() {
	DType D{ 62, 8, 90, 2, 24, 62, 38, 64, 76, 60, 30, 76, 80, 74, 72 };
	return D;
}
bool Show(bool F) {
	std::cout << (F ? "possible" : "impossible") << std::endl;
	return true;
}

bool MoveElement(DType& A, DType& B, std::size_t Idx) {
	A.push_back(B[Idx]);
	B.erase(B.begin() + Idx);
	return true;
}

bool MakeHoge_r(DType A, DType B) {
	std::uint64_t WA = Sum(A);
	std::uint64_t WB = Sum(B);

	if (WA == WB) return true;
	if (WA > WB) return false;
	auto TA = A;
	auto TB = B;
	for (std::size_t i = 0; i < B.size()/2; i++) {
		MoveElement(A, B, i);
		if (MakeHoge_r(A, B) == true)return true;
		A = TA;
		B = TB;
	}
	return false;
}

bool MakeHoge(DType& D) {
	
	DType T;

	return MakeHoge_r(T, D);
}

int main() {
	DType D;
	bool F = false;

#if !GSI
	D = MakeProblem1();
	F = MakeHoge(D);
	Show(F);
	D = MakeProblem2();
	F = MakeHoge(D);
	Show(F);
	D = MakeProblem3();
	F = MakeHoge(D);
	Show(F);
#else
	D = GetInput();
	F = MakeHoge(D);
	Show(F);
#endif
	return 0;
}