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 pi = acos(-1.0);
const double eps = 1e-8;
inline int sign(double x) {
  if (x < -eps) return -1;
  return x > eps;
}
struct Tpoint {
  double x, y;
  Tpoint() {}
  Tpoint(double x, double y) : x(x), y(y) {}
  inline double norm() { return sqrt(x * x + y * y); }
  inline void rotate(double ang) {
    double co = cos(ang), si = sin(ang);
    double tx = x, ty = y;
    x = tx * co - ty * si;
    y = tx * si + ty * co;
  }
};
inline Tpoint operator+(const Tpoint &a, const Tpoint &b) {
  return Tpoint(a.x + b.x, a.y + b.y);
}
inline Tpoint operator-(const Tpoint &a, const Tpoint &b) {
  return Tpoint(a.x - b.x, a.y - b.y);
}
inline Tpoint operator*(const Tpoint &a, const double &b) {
  return Tpoint(a.x * b, a.y * b);
}
inline Tpoint operator/(const Tpoint &a, const double &b) {
  return Tpoint(a.x / b, a.y / b);
}
inline double det(const Tpoint &a, const Tpoint &b) {
  return a.x * b.y - a.y * b.x;
}
inline double dot(const Tpoint &a, const Tpoint &b) {
  return a.x * b.x + a.y * b.y;
}
int n, m;
int x[1000000], y[1000000];
int main() {
  scanf("%d%d", &n, &m);
  if (m == 3 && n > 4) {
    puts("-1");
    return 0;
  }
  int head = 0, tail = m, sum = -2;
  for (int i = 1; i <= m; ++i) {
    x[tail] = i;
    y[tail] = m * m + 10 + i * i;
    x[head] = i;
    y[head] = -m * m - 10 - i * i;
    ++tail;
    ++head;
  }
  for (int i = 0; i < n; ++i) {
    printf("%d %d\n", x[i], y[i]);
  }
  return 0;
}