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 N_ = 305, M_ = 305;
const int INF = 987654321;
int N, M;
int main() {
  int i, j, k;
  scanf("%d%d", &N, &M);
  if (M == 3) {
    if (N == 3) {
      puts("0 0");
      puts("0 10");
      puts("10 0");
    } else if (N == 4) {
      puts("0 0");
      puts("0 3");
      puts("3 0");
      puts("1 1");
    } else if (N == 5) {
      puts("-1");
    } else if (N == 6) {
      puts("-1");
    }
    return 0;
  }
  for (i = 1; i <= M; i++) {
    printf("%d %d\n", i, i * i);
  }
  i = 100000;
  j = 0;
  k = M * 2 - N;
  while (j < N - M) {
    ++j;
    ++k;
    printf("%d %d\n", i--, k * k);
  }
  return 0;
}