#include <bits/stdc++.h>

#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define F first
#define S second
#define pb push_back
#define ll long long

//#define PROBLEM "solid"

using namespace std;

const int MAXN = 1000;
const int INF = 1e7;

int main() {
    #ifndef LOCAL
        #ifdef PROBLEM
            freopen(PROBLEM".in", "r", stdin);
            freopen(PROBLEM".out", "w", stdout);
        #endif
    #endif
    #ifdef LOCAL
        //freopen("/Users/alekseygolub/Desktop/С++/ABS/ABS/input.txt", "r", stdin);
    #endif
    cin.tie(0);
    cout.tie(0);
    ios_base::sync_with_stdio(0);
//---------------------------------------------------------------------------------------------------------
    int n, m;
    cin >> n >> m;
    if (n != m && m != ((n*(n - 1)) / 2)) {
        cout << "Impossible";
        return 0;
    }
    set<pair<int, int>> ans;
    cout << "Possible" << '\n';
    if (n == m) {
        for (int i = 1; i < n; i++) {
            int j = i + 1;
            ans.insert({min(i, j), max(i, j)});
        }
        ans.insert({1, n});
    } else {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                if (i != j)
                    ans.insert({min(i, j), max(i, j)});
            }
        }
    }
    for (auto x: ans) {
        if (x.F == x.S) throw new exception;
        cout << x.F << " " << x.S << endl;
    }
    return 0;
}