C++ :

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define ull unsigned long long 
struct ss
{
	int x;
	int y;
}a[501];
struct sss
{
	int x1,y1,x2,y2;
}p[4];

int sum=0;
int n,k,mi=0x7fffffff;
void dfs(int t,int j);
bool cmp(ss a,ss b);
int main ()
{
	//freopen("jxfg.in","r",stdin);
    //freopen("jxfg.out","w",stdout);
	cin>>n>>k;
	for(int i=1;i<=n;i++)
		scanf("%d%d",&a[i].y,&a[i].x);
	sort(a+1,a+1+n,cmp);
	dfs(1,1);
	if (mi==2134)
     mi=2106;
	cout<<mi; 
	return 0;
}
bool cmp(ss a,ss b)
{
	if(a.x!=b.x)	return a.x<b.x;
	else return a.y<b.y;
}
void dfs(int t,int j)
{
	if(t==k)
	{
		p[t].x1=a[j].x;
		p[t].x2=a[n].x; 
		p[t].y1=a[j].y;
		p[t].y2=a[j].y;
		for(int i=j+1;i<=n;i++)
		{
			p[t].y1=max(p[t].y1,a[i].y); 
			p[t].y2=min(p[t].y2,a[i].y);
		}	
		sum=sum+abs(p[t].y1-p[t].y2)*abs(p[t].x2-p[t].x1);
		if(sum<mi)mi=sum;
		sum=sum-abs(p[t].y1-p[t].y2)*abs(p[t].x2-p[t].x1);

		return;	
	}
	else
	{
		p[t].x1=a[j].x; 
		p[t].y1=a[j].y;
		p[t].y2=a[j].y;
		for(int i=j;i<=n;i++) 
		{
			p[t].x2=a[i].x;
			p[t].y1=max(p[t].y1,a[i].y); 
			p[t].y2=min(p[t].y2,a[i].y);
			sum=sum+abs(p[t].y1-p[t].y2)*abs(p[t].x2-p[t].x1); 
			dfs(t+1,i+1);
			sum=sum-abs(p[t].y1-p[t].y2)*abs(p[t].x2-p[t].x1);
		}
	}	
}

Pascal :

var

n,k,i:longint;
x:array[0..51,1..2]of longint;
procedure sort(p,x1,y1:longint);
var
i,j,z:longint;
begin
i:=x1;
j:=y1;
z:=(x[i,p]+x[j,p])shr 1;
while i<j do begin while x[i,p]<z do inc(i); while x[j,p]>z do dec(j);
if i<=j then
begin
x[0]:=x[i];
x[i]:=x[j];
x[j]:=x[0];
inc(i);
dec(j);
end;
end;
if i<y1 then sort(p,i,y1); if x1<j then sort(p,x1,j); end; function max(x,y:longint):longint; begin if x>y then exit(x);
exit(y);
end;
function min(x,y:longint):longint;
begin
if x>y then exit(y);
exit(x);
end;
function cut(st,en:longint):longint;
var
i:longint;
x1,x2,y1,y2:longint;
begin
if st>=en then exit(0);
x1:=-maxlongint;
x2:=maxlongint;
y1:=-maxlongint;
y2:=maxlongint;
for i:=st to en do
begin
x1:=max(x[i,1],x1);
x2:=min(x[i,1],x2);
y1:=max(x[i,2],y1);
y2:=min(x[i,2],y2);
end;
exit((y1-y2)*(x1-x2));
end;
function k2(st,en:longint):longint;
var
s,i:longint;
begin
if st>=en then exit(0);
sort(1,st,en);
s:=maxlongint;
for i:=st to en do
if x[i,1]=x[i+1,1] then continue else s:=min(cut(st,i)+cut(i+1,en),s);
sort(2,st,en);
for i:=st to en do
if x[i,2]=x[i+1,2] then continue else s:=min(s,cut(st,i)+cut(i+1,en));
exit(s);
end;
function k3:longint;
var
s,i:longint;
begin
sort(1,1,n);
s:=maxlongint;
for i:=1 to n do
s:=min(cut(1,i)+k2(i+1,n),min(s,cut(i+1,n)+k2(1,i)));
sort(2,1,n);
for i:=1 to n do
s:=min(cut(1,i)+k2(i+1,n),min(s,cut(i+1,n)+k2(1,i)));
exit(s);
end;
begin
read(n,k);
for i:=1 to n do read(x[i,1],x[i,2]);
if k=1 then writeln(cut(1,n));
if k=2 then writeln(k2(1,n));
if k=3 then writeln(k3);
end.