Buggy python submission (verdict: Time Limit Exceeded):
# -*- coding: utf-8 -*-
from itertools import combinations

n,k = map(int, input().split())

xl = []
yl = []
xy = []
for _ in range(n):
    x,y = map(int, input().split())
    xl.append(x)
    yl.append(y)
    xy.append((x,y))

res = None
for cx in combinations(xl, 2):
    for cy in combinations(yl, 2):
        x1,x2 = cx
        y1,y2 = cy

        if x2>x1:
            x1,x2 = x2,x1
        if y2>y1:
            y1,y2 = y2,y1

        cnt = 0
        for cc in xy:
            x,y = cc
            if x1>=x>=x2 and y1>=y>=y2:
                cnt += 1
            if cnt>=k:
                break
        if cnt>=k:
            s = (x1-x2)*(y1-y2)
            if res is None:
                res = s
            else:
                res = min(res, s)

print(res)


Fixed submission:
# -*- coding: utf-8 -*-
from itertools import combinations

n,k = map(int, input().split())

xl = []
yl = []
xy = []
for _ in range(n):
    x,y = map(int, input().split())
    xl.append(x)
    yl.append(y)
    xy.append((x,y))
yl.sort()
xy.sort(key=lambda x:x[1])

res = None
for cx in combinations(xl, 2):
    x1,x2 = cx
    if x2>x1:
        x1,x2 = x2,x1

    for y2 in yl:
        cnt = 0
        for c in xy:
            x,y = c
            if x1>=x>=x2 and y>=y2:
                cnt += 1

            if cnt==k:
                y1 = y
                s = (x1-x2)*(y1-y2)
                if res is None:
                    res = s
                else:
                    res = min(res, s)
                break

print(res)

Buggy python submission (verdict: Time Limit Exceeded):
# -*- coding: utf-8 -*-
from itertools import combinations

n,k = map(int, input().split())
pary = []
xary = []
yary = []
for _ in range(n):
    x,y = map(int, input().split())
    pary.append([x,y])
    xary.append(x)
    yary.append(y)

ret = None
for x in combinations(range(n),2):
    for y in combinations(range(n),2):
        xc = [xary[x[0]], xary[x[1]]]
        yc = [yary[y[0]], yary[y[1]]]
        cnt = 0
        for p in pary:
            if (min(xc[0],xc[1])<=p[0]<=max(xc[0],xc[1])
                and min(yc[0],yc[1])<=p[1]<=max(yc[0],yc[1])):
                cnt += 1
            if cnt==k:
                break
        if cnt>=k:
            s = abs(xc[0]-xc[1]) * (abs(yc[0]-yc[1]))
            if ret is None:
                ret = s
            else:
                ret = min(ret,s)

print(ret)


Fixed submission:
# -*- coding: utf-8 -*-
from itertools import combinations

n,k = map(int, input().split())

xl = []
yl = []
xy = []
for _ in range(n):
    x,y = map(int, input().split())
    xl.append(x)
    yl.append(y)
    xy.append((x,y))
yl.sort()
xy.sort(key=lambda x:x[1])

res = None
for cx in combinations(xl, 2):
    x1,x2 = cx
    if x2>x1:
        x1,x2 = x2,x1

    for y2 in yl:
        cnt = 0
        for c in xy:
            x,y = c
            if x1>=x>=x2 and y>=y2:
                cnt += 1

            if cnt==k:
                y1 = y
                s = (x1-x2)*(y1-y2)
                if res is None:
                    res = s
                else:
                    res = min(res, s)
                break

print(res)