#include <iostream>

using namespace std;

int main() {
	int R, C;
	cin >> R >> C;

	int Rsum = 0;
	for (int i=0; i<R; i++) {
		int k;
		cin >> k;
		Rsum += k;
	}

	int Csum = 0;
	for (int i=0; i<C; i++) {
		int k;
		cin >> k;
		Csum += k;
	}

	if (Rsum == Csum)
		cout << "possible" << endl;
	else
		cout << "impossible" << endl;

	return 0;
}