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 pisz(int n) { printf("%d\n", n); }
template <typename T, typename TT>
ostream& operator<<(ostream& s, pair<T, TT> t) {
  return s << "(" << t.first << "," << t.second << ")";
}
template <typename T>
ostream& operator<<(ostream& s, vector<T> t) {
  for (int(i) = 0; (i) < (((int)((t).size()))); ++(i)) s << t[i] << " ";
  return s;
}
int main() {
  int(n), (m);
  scanf("%d %d", &(n), &(m));
  if (m == 3) {
    if (n == 6 || n == 5) {
      pisz(-1);
    } else if (n == 4) {
      printf("0 0\n3 0\n0 3\n1 1");
    } else if (n == 3) {
      printf("0 0\n3 0\n0 3");
    }
  } else {
    int y = 0;
    vector<pair<int, int> > v;
    v.push_back(make_pair(1, 0));
    for (int k = m; k >= 2; --k) {
      v.push_back(make_pair(m + 2 - k, y += k));
    }
    for (int(i) = 0; (i) < (n - m); ++(i)) {
      v.push_back(make_pair(-v[i].first - 1000, v[i].second));
    }
    for (typeof(v.begin()) it = v.begin(); it != v.end(); it++)
      printf("%d %d\n", it->first, it->second);
  }
}