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 int R = (5e6) + 64;
const double Pi = acos(-1.0);
const double pro = 0.8;
const double alpha = 0.0001;
int ans[201][2];
int main() {
  int m, n;
  scanf("%d%d", &n, &m);
  if (3 == m && n >= 5) {
    printf("-1\n");
    return 0;
  }
  double beta = 2 * Pi / m;
  for (int i = 0; i < m; i++) {
    ans[i][0] = R * cos(beta * i);
    ans[i][1] = R * sin(beta * i);
  }
  for (int i = 0; i < m; i++) {
    int x = pro * ans[i][0], y = pro * ans[i][1];
    ans[i + m][0] = (int)(x * cos(alpha) - y * sin(alpha));
    ans[i + m][1] = (int)(y * cos(alpha) + x * sin(alpha));
  }
  for (int i = 0; i < n; i++) printf("%d %d\n", ans[i][0], ans[i][1]);
  return 0;
}