#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<queue>
#include<cmath>
#include<functional>
using namespace std;
int n, m;
int main() {
	cin >> n >> m;
	if (n*(n + 1) / 2 < m)cout << "Impossible" << endl;
	else if ((n == 1 && m == 0) || (n == 2 && m == 0))cout << "Impossible" << endl;
	else cout << "Possible" << endl;
	return 0;
}