#include <iostream>

using namespace std;

int main()
{
    int n, m;
    cin >> n >> m;
    if (n != m) {
        cout << "Impossible";
        return 0;
    }
    cout << "Possible" << '\n';
    for (int i = 1; i < n; i++) {
        cout << i << ' ' << i + 1 << '\n';
    }
    cout << 1 << ' ' << n;
    return 0;
}