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;
long long int ve_m(int x, int y, int xx, int yy) {
  return (x * 1LL * yy) - (xx * 1LL * y);
}
int n, m;
vector<pair<int, int> > p;
void Init() {
  scanf("%d%d", &n, &m);
  if (m == 3) {
    if (n > 4) {
      printf("-1\n");
      exit(0);
    }
    printf("0 0\n");
    printf("0 3\n");
    printf("3 0\n");
    if (n == 4) {
      printf("1 1\n");
    }
    exit(0);
  }
}
void solve() {
  int x, y, xx, yy, kx, ky;
  printf("0 0\n");
  printf("100000 0\n");
  printf("-1 -2\n");
  printf("100001 -2\n");
  p.push_back(make_pair(0, 0));
  p.push_back(make_pair(100000, 0));
  p.push_back(make_pair(-1, -2));
  p.push_back(make_pair(100001, -2));
  x = -1;
  y = -2;
  xx = 100001;
  yy = -2;
  n -= 4;
  m -= 4;
  kx = 2;
  ky = 3;
  while (m != n) {
    x -= kx;
    y -= ky;
    printf("%d %d\n", x, y);
    p.push_back(make_pair(x, y));
    n--;
    if (n == m) break;
    xx += kx;
    yy -= ky;
    printf("%d %d\n", xx, yy);
    p.push_back(make_pair(xx, yy));
    kx++;
    ky++;
    n--;
  }
  kx = 2;
  for (int i = 0; i < m; i++) {
    x += kx;
    y--;
    bool flag = false;
    for (int k = 0; k < p.size(); k++) {
      for (int j = 0; j < p.size(); j++) {
        if (k != j) {
          if (ve_m(p[k].first - x, p[k].second - y, p[j].first - x,
                   p[j].second - y) == 0) {
            flag = true;
          }
        }
      }
    }
    if (!flag)
      printf("%d %d\n", x, y);
    else {
      i--;
    }
    kx++;
  }
}
int main() {
  Init();
  solve();
  return 0;
}