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>
const long long INF = 9999999999999;
using namespace std;
string getNewString(string x) {
  int j = x.size() - 1;
  while (1) {
    if (x[j] < 'z') {
      x[j] += 1;
      break;
    } else {
      x[j] = 'a';
      if (!j) {
        x.push_back('a');
        break;
      }
      j--;
    }
  }
  return x;
}
int main() {
  long long n, m;
  cin >> n >> m;
  long long x = 1e6, y = 1e6 + 1;
  if (m == 3 && n > 4) {
    cout << -1 << endl;
    return 0;
  }
  for (long long i = 0; i < m; ++i) {
    cout << x << " " << y << endl;
    x++;
    y += (i + 2) * 2;
  }
  x = 1e6, y = -1e6 - 1;
  for (long long i = 0; i < n - m; ++i) {
    cout << x << " " << y << endl;
    x++;
    y -= (i + 2) * 2;
  }
  return 0;
}