#include <bits/stdc++.h>
using namespace std;
const int MX = 1147483646;
const long long MX2 = 3223372036854775800;
const int MOD = 998244353;
int gcd(int x, int y) { return y ? gcd(y, x % y) : x; }
vector<pair<int, int> > v;
void ans() {
  cout << "Possible\n";
  for (pair<int, int> x : v) cout << x.first << " " << x.second << "\n";
  exit(0);
}
int main() {
  cin.tie(NULL);
  ios::sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  int i;
  for (i = 2; i <= n; i++) {
    v.push_back({1, i});
    m--;
  }
  if (m < 0) goto fail;
  if (m == 0) ans();
  int j;
  for (i = 2; i <= n; i++) {
    for (j = i + 1; j <= n; j++) {
      if (gcd(i, j) == 1) {
        v.push_back({i, j});
        m--;
      }
      if (m == 0) ans();
      if (i % 2 == 0) j++;
    }
  }
fail:
  cout << "Impossible";
  return 0;
}
