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 r1 = 1000000;
pair<int, int> mv(pair<int, int> x) { return x; }
int main() {
  int n, m;
  cin >> n >> m;
  if (m == 3 && n > 4) {
    cout << -1 << endl;
    return 0;
  }
  vector<pair<int, int> > V;
  for (register int i = (0); i < (int)(m); ++i) {
    double deg = M_PI * i / (m - 1);
    V.push_back(mv(
        pair<int, int>(round(r1 * sin(deg)) - r1 * 3, round(r1 * cos(deg)))));
  }
  for (register int i = (0); i < (int)(n - m); ++i) {
    double deg = M_PI + M_PI * i / (m - 1);
    V.push_back(mv(
        pair<int, int>(round(r1 * sin(deg)) + r1 * 3, round(r1 * cos(deg)))));
  }
  for (register int i = (0); i < (int)(((int)(V).size())); ++i)
    cout << V[i].first << " " << V[i].second << endl;
  return 0;
}