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>
#pragma comment(linker, "/STACK:200000000")
using namespace std;
template <typename T>
inline T Abs(T x) {
  return (x >= 0) ? x : -x;
}
template <typename T>
inline T sqr(T x) {
  return x * x;
}
template <typename T>
string toStr(T x) {
  stringstream st;
  st << x;
  string s;
  st >> s;
  return s;
}
inline int nextInt() {
  int x;
  if (scanf("%d", &x) != 1) throw;
  return x;
}
inline long long nextInt64() {
  long long x;
  if (scanf("%I64d", &x) != 1) throw;
  return x;
}
inline double nextDouble() {
  double x;
  if (scanf("%lf", &x) != 1) throw;
  return x;
}
const int INF = (int)1E9;
const long long INF64 = (long long)1E18;
const long double EPS = 1E-9;
const long double PI = 3.1415926535897932384626433832795;
const int MAXN = 100100;
int main() {
  int n = nextInt();
  int m = nextInt();
  if (m == 3 && 5 <= n && n <= 6) {
    cout << -1 << endl;
    return 0;
  }
  if (n == 4 && m == 3) {
    cout << "0 0" << endl;
    cout << "3 0" << endl;
    cout << "0 3" << endl;
    cout << "1 1" << endl;
    return 0;
  }
  for (int i = 0; i < (int)(m); i++) {
    int x = i - m / 2;
    int y = +4 * sqr(x) + 1000 * 10000;
    cout << x << " " << y << endl;
  }
  for (int i = 0; i < (int)(n - m); i++) {
    int x = i - (n - m) / 2;
    int y = -4 * sqr(x) - 1000 * 10000;
    cout << x << " " << y << endl;
  }
  return 0;
}