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;
struct point {
  int x, y;
  point(int x = 0, int y = 0) : x(x), y(y) {}
};
int n, m;
vector<point> ans;
const int C = 30000000;
void Input() { cin >> n >> m; }
void Solve() {
  for (int i = 0; i < m; i++) ans.push_back(point(i, (i * (i + 1)) / 2));
  for (int i = 0; i < n - m; i++)
    ans.push_back(point(-i + C, (i * (i + 1)) / 2));
}
int main() {
  Input();
  if ((n == 6 && m == 3) || (n == 5 & m == 3)) {
    cout << -1 << endl;
    return 0;
  }
  Solve();
  for (int i = 0; i < ans.size(); i++)
    cout << ans[i].x << " " << ans[i].y << endl;
  return 0;
}