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 MAXN = 256;
const int R = 50000000 + 86;
const int STEP = 32;
const double PI = acos(-1.0);
const double RATE = 0.888;
int x[MAXN], y[MAXN];
bool aline(int i, int j, int k) {
  return (long long)(x[i] - x[j]) * (long long)(y[i] - y[k]) ==
         (long long)(y[i] - y[j]) * (long long)(x[i] - x[k]);
}
void check(int n, int m) {
  for (int i = 0; i < n; ++i)
    for (int j = i + 1; j < n; ++j)
      for (int k = j + 1; k < n; ++k) {
        if (aline(i, j, k)) {
          puts("MOMO");
          return;
        }
      }
  puts("OK");
}
int main() {
  int i, j, k;
  int m, n;
  double delta;
  scanf("%d%d", &n, &m);
  if (m == 3 && n >= 5) {
    puts("-1");
    return 0;
  }
  delta = 2 * PI / m;
  for (i = 0; i < m; ++i) {
    x[i] = (int)floor(R * cos(delta * i));
    y[i] = (int)floor(R * sin(delta * i));
  }
  for (i = 0; i < m; ++i) {
    int xx = (int)floor(x[i] * RATE), yy = (int)floor(y[i] * RATE);
    double momo = delta / STEP;
    x[i + m] = xx * cos(momo) - yy * sin(momo);
    y[i + m] = yy * cos(momo) + xx * sin(momo);
  }
  for (i = 0; i < n; ++i) printf("%d %d\n", x[i], y[i]);
  return 0;
}