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;
int n, m;
vector<pair<int, int> > res;
const int R1 = 1e7, R2 = 2e7;
long long det(pair<int, int> a, pair<int, int> b) {
  return 1ll * a.first * b.second - 1ll * a.second * b.first;
}
pair<int, int> seg(pair<int, int> a, pair<int, int> b) {
  return pair<int, int>(a.first - b.first, a.second - b.second);
}
int main() {
  scanf("%d%d", &n, &m);
  if (m == 3 && n >= 5) return puts("-1"), 0;
  for (int i = 0; i < m; i++)
    res.push_back(
        pair<int, int>(R1 * cos(2 * M_PI * i / m), R1 * sin(2 * M_PI * i / m)));
  for (int i = 0; i < n - m; i++)
    res.push_back(pair<int, int>(R2 * cos(2 * M_PI * i / m + M_PI * 0.0001),
                                 R2 * sin(2 * M_PI * i / m + M_PI * 0.0001)));
  for (int i = 0; i < n; i++) printf("%d %d\n", res[i].first, res[i].second);
  return 0;
}