#include <iostream>

using namespace std;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	string H, S;
	H.reserve(200'002), S.reserve(200'002);
	cin >> H >> S;

	if (H[H.size() - 1] - S[S.size() - 1] & 1) cout << "Impossible\n";
	else cout << "Possible\n";

	return 0;
}