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;
const double pi = acos(-1.0);
const int inf = (int)1e9;
const double eps = 1e-7;
const int ss = (int)1e6 + 3;
const int base = inf;
bool pred1(const pair<int, int>& i, const pair<int, int>& j) {
  if (i.first == j.first)
    return i.second > j.second;
  else
    return i.first > j.first;
}
int n, m;
int main() {
  scanf("%d%d", &n, &m);
  if (m == 3 && n >= 5) {
    cout << -1;
    return 0;
  }
  for (int i = 0; i < m; ++i) {
    cout << -(m - i) << " " << (i + 1) * (i + 1) << endl;
  }
  for (int i = 0; i < n - m; ++i) {
    cout << i + 1 << " " << -((n - m - i) * (n - m - i)) << endl;
  }
  return 0;
}