#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
using namespace std;

int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<'0' || ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0' && ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
struct point
{
    int x,y;
}a[60];

int cmp(point a,point b)
{
    if(a.x==b.x)return a.y<b.y;
    return a.x<b.x;
}

struct block
{
    int x1,y1,x2,y2;
}b[5];

int n,k;
int ans=1e3;

void DFS(int pos,int cnt,int smm)
{
    if(pos>n)
	{
        ans=min(ans,smm);
        return;
    }
    
    if(cnt>k)
	{
		return;
	}
    int i,j;
    
    b[cnt].x1=a[pos].x;
    b[cnt].x2=a[pos].x;
    b[cnt].y1=a[pos].y;
    b[cnt].y2=a[pos].y;
    
    for(i=pos;i<=n;i++)
	{
        b[cnt].y2=max(b[cnt].y2,a[i].y);
        b[cnt].x2=max(b[cnt].x2,a[i].x);
        b[cnt].x1=min(b[cnt].x1,a[i].x);
        b[cnt].y1=min(b[cnt].y1,a[i].y);
        
        for(j=1;j<cnt;j++)
		{
            if(b[cnt].x1<=b[j].x2 && b[cnt].y1<=b[j].y2)
			{
				return;
			}
        }
        
        if(i<n && cnt==k)
		{
			continue;
		}
		
        DFS(i+1,cnt+1,smm+(b[cnt].x2-b[cnt].x1)*(b[cnt].y2-b[cnt].y1));
    }
    return;
}

int main()
{
    n=read();k=read();
    int i,j;
    
    for(i=1;i<=n;i++)
	{
        a[i].y=read();a[i].x=read();
    }
    sort(a+1,a+n+1,cmp);
    memset(b,-1,sizeof b);
    DFS(1,1,0);
    printf("%d\n",ans);
    return 0;
}