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;
inline void read(int &a) {
  a = 0;
  int c = getchar(), b = 1;
  while (c > '9' || c < '0') {
    if (c == '-') b = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') a = (a << 3) + (a << 1) + c - 48, c = getchar();
  a *= b;
}
inline int Rem() {
  int a = 0, c = getchar(), b = 1;
  while (c > '9' || c < '0') {
    if (c == '-') b = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') a = (a << 3) + (a << 1) + c - 48, c = getchar();
  return a *= b;
}
inline void write(int x) {
  if (x > 9) write(x / 10);
  putchar('0' + x % 10);
}
inline void W(int x) {
  if (x < 0) {
    putchar('-'), x = -x;
  }
  write(x);
}
int n, m;
int main() {
  read(n), read(m);
  if (m == 3 && n > 4) {
    puts("-1");
    return 0;
  }
  for (int i = 1; i <= m; i++) {
    cout << i << " " << 1000000 + i * i << "\n";
  }
  for (int i = 1; i <= n - m; i++) {
    cout << i << " " << -1000000 - i * i << "\n";
  }
}