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;
void run();
int main() {
  ios::sync_with_stdio(0);
  run();
}
void run() {
  int n, m;
  cin >> n >> m;
  int z = n - m;
  if (m == 3 and n >= 5) {
    cout << "-1" << endl;
    return;
  }
  long long grad = m - 2;
  long long ay = 0, by = 10000007ll;
  for (long long x = 0; x < m; ++x, --grad) {
    if (true) {
      cout << x << " " << ay << endl;
      ay += grad;
    }
    if (x < z) {
      cout << x << " " << by << endl;
      by -= grad;
    }
  }
}