Problem: Convexity of a set of points on the plane is the size of the largest subset of points that form a convex polygon. Your task is to build a set of n points with the convexity of exactly m. Your set of points should not contain three points that lie on a straight line.

Input

The single line contains two integers n and m (3 ≤ m ≤ 100, m ≤ n ≤ 2m).

Output

If there is no solution, print "-1". Otherwise, print n pairs of integers — the coordinates of points of any set with the convexity of m. The coordinates shouldn't exceed 108 in their absolute value.

Examples

Input

4 3


Output

0 0
3 0
0 3
1 1


Input

6 3


Output

-1


Input

6 6


Output

10 0
-10 0
10 1
9 1
9 -1
0 -2


Input

7 4


Output

176166 6377
709276 539564
654734 174109
910147 434207
790497 366519
606663 21061
859328 886001

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
template <typename S, typename T>
ostream& operator<<(ostream& out, pair<S, T> const& p) {
  out << '(' << p.first << ", " << p.second << ')';
  return out;
}
template <typename T>
ostream& operator<<(ostream& out, vector<T> const& v) {
  int l = v.size();
  for (int i = 0; i < l - 1; i++) out << v[i] << ' ';
  if (l > 0) out << v[l - 1];
  return out;
}
template <typename T>
void trace(const char* name, T&& arg1) {
  cout << name << " : " << arg1 << endl;
}
template <typename T, typename... Args>
void trace(const char* names, T&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cout.write(names, comma - names) << " : " << arg1 << " | ";
  trace(comma + 1, args...);
}
const long double PI = 3.1415926535897932384626433832795;
int n, m, x = 1e7;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> m;
  if (m == 3 and (n == 5 or n == 6)) {
    cout << -1 << '\n';
    return 0;
  } else if (m == 3) {
    if (n == 3) {
      cout << 0 << ' ' << 0 << endl;
      cout << 0 << ' ' << 1 << endl;
      cout << 1 << ' ' << 0 << endl;
      return 0;
    } else if (n == 4) {
      cout << 0 << ' ' << 0 << endl;
      cout << 0 << ' ' << 10 << endl;
      cout << 10 << ' ' << 0 << endl;
      cout << 1 << ' ' << 1 << endl;
      return 0;
    }
  }
  for (int i = 0; i < m; i++) cout << i << ' ' << x + i * i << endl;
  for (int i = 0; i < n - m; i++) cout << i << ' ' << -x - i * i << endl;
  return 0;
}