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;
void openFiles() {
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
}
const int d = 100 * 1000 * 1000;
void solve() {
  int n, m;
  cin >> n >> m;
  if (n == 6 && m == 3 || n == 5 && m == 3) {
    cout << -1;
    return;
  }
  vector<int> x, y;
  int curx = 0;
  int cury = 0;
  int dy = 100 * 100;
  int dx = 0;
  for (int i = 0; i < m - 1; ++i) {
    x.push_back(curx);
    y.push_back(cury);
    curx += dx;
    cury += dy;
    dx = 1000 * 1000;
    --dy;
  }
  x.push_back(curx - dx);
  if (m == 3) x.back() += dx;
  y.push_back(0);
  int rest = n - m;
  if (rest == 0) {
    for (int i = 0; i < n; ++i) cout << x[i] - d << " " << y[i] << endl;
    return;
  }
  if (rest == 1) {
    x.push_back(1);
    y.push_back(1);
    for (int i = 0; i < n; ++i) cout << x[i] - d << " " << y[i] << endl;
    return;
  }
  if (rest == 2) {
    x.push_back(1);
    y.push_back(1);
    x.push_back(x[m - 1] - 1);
    y.push_back(1);
    for (int i = 0; i < n; ++i) cout << x[i] - d << " " << y[i] << endl;
    return;
  }
  if (rest == 3) {
    x.push_back(1);
    y.push_back(1);
    x.push_back(x[m - 1] - 1);
    y.push_back(1);
    x.push_back(x[m - 1] - 1);
    y.push_back(y[m - 2] - 1);
    for (int i = 0; i < n; ++i) cout << x[i] - d << " " << y[i] << endl;
    return;
  }
  curx = 1;
  cury = 1;
  dy = 299;
  dx = 0;
  for (int i = 0; i < rest - 1; ++i) {
    if (i == rest - 2) curx = x[m - 1] - 1;
    x.push_back(curx);
    y.push_back(cury);
    curx += dx;
    cury += dy;
    dx = 1000 * 1000;
    if (i) --dy;
  }
  y.back()--;
  x.push_back(x[m - 1] - 1);
  y.push_back(1);
  for (int i = 0; i < n; ++i) cout << x[i] - d << " " << y[i] << endl;
}
int main() {
  ios_base::sync_with_stdio(0);
  solve();
  return 0;
}