Problem:
Score : 400 points

Problem Statement

We have N points in a two-dimensional plane.

The coordinates of the i-th point (1 \leq i \leq N) are (x_i,y_i).

Let us consider a rectangle whose sides are parallel to the coordinate axes that contains K or more of the N points in its interior.

Here, points on the sides of the rectangle are considered to be in the interior.

Find the minimum possible area of such a rectangle.

Constraints

2 \leq K \leq N \leq 50

-10^9 \leq x_i,y_i \leq 10^9 (1 \leq i \leq N)

x_i≠x_j (1 \leq i<j \leq N)

y_i≠y_j (1 \leq i<j \leq N)

All input values are integers. (Added at 21:50 JST)

Input

Input is given from Standard Input in the following format:

N K
x_1 y_1
:
x_{N} y_{N}

Output

Print the minimum possible area of a rectangle that satisfies the condition.

Sample Input 1

4 4
1 4
3 3
6 2
8 1

Sample Output 1

21

One rectangle that satisfies the condition with the minimum possible area has the following vertices: (1,1), (8,1), (1,4) and (8,4).

Its area is (8-1) × (4-1) = 21.

Sample Input 2

4 2
0 0
1 1
2 2
3 3

Sample Output 2

1

Sample Input 3

4 3
-1000000000 -1000000000
1000000000 1000000000
-999999999 999999999
999999999 -999999999

Sample Output 3

3999999996000000001

Watch out for integer overflows.

Solution in Python (3.4.3) (judge verdict: Wrong Answer)

#from numpy import*
#from scipy import*
from collections import* #defaultdict Counter deque appendleft
from fractions import gcd
from functools import* #reduce
from itertools import* #permutations("AB",repeat=2) combinations("AB",2) product("AB",2) groupby
from operator import mul
from bisect import* #bisect_left bisect_right
from heapq import* #heapify heappop heappushpop
from math import factorial,pi
from copy import deepcopy
import sys
#input=sys.stdin.readline  #危険！基本オフにしろ！
sys.setrecursionlimit(10**6)



def main():
    n,k=map(int,input().split())
    grid=[list(map(int,input().split()))for i in range(n)]
    ans=[]
    dx=sorted(grid,key=lambda x:x[0])
    for i in range(n-k+1):
        v=dx[i:i+k]
        y=set(t for s,t in v)
        #print(v)
        ans.append((v[-1][0]-v[0][0])*(max(y)-min(y)) )
    #dy=sorted(grid,key=lambda x:x[1])
    #for i in range(n-k+1):
    #    v=dy[i:i+k]
    #    x=set(s for s,t in v)
    #    ans.append((v[-1][1]-v[0][1])*(max(x)-min(x)) )
    print(max(ans))
    
    
if __name__ == '__main__':
    main()