#include<iostream>
#include<cmath>
using namespace std;
const double PI=acos(-1.0);
int n,l;
typedef struct point
{
double x,y;
point(double xx=0,double yy=0):x(xx),y(yy){}
}vector;
point p[1010],q[1010];
void sort1(point *a,int x,int y,point *t)
{
int m,u,v,i;
if(y-x>1)
{
m=x+(y-x)/2;
u=x,v=m,i=x;
sort1(a,x,m,t);
sort1(a,m,y,t);
while(u<m || v<y)
{
if(v>=y || (u<m && (a[u].x<a[v].x || (a[u].x==a[v].x && a[u].y<=a[v].y)))) t[i++]=a[u++];
else t[i++]=a[v++];
}
for(i=x;i<y;i++) a[i]=t[i];
}
}
vector operator - (point a,point b) {return vector(a.x-b.x,a.y-b.y);}
double cross(vector a,vector b)
{
return a.x*b.y-a.y*b.x;
}
int convex(point *a,point *t)
{
int k,m=0,i;
for(i=0;i<n;i++)
{
while(m>1 && cross(t[m-1]-t[m-2],a[i]-t[m-2])<=0) m--;
t[m++]=a[i];
}
k=m;
for(i=n-1;i>=0;i--)
{
while(m>k && cross(t[m-1]-t[m-2],a[i]-t[m-2])<=0) m--;
t[m++]=a[i];
}
if(n>1) m--;
return m;
}
double dot(vector a,vector b)
{
return a.x*b.x+a.y*b.y;
}
double length(vector a)
{
return sqrt(dot(a,a));
}
int main()
{
int i,m;
double s;
while(cin>>n>>l)
{
s=0.0;
for(i=0;i<n;i++)
cin>>p[i].x>>p[i].y;
sort1(p,0,n,q);
m=convex(p,q);
for(i=0;i<m;i++)
{
s+=length(q[i]-q[(i+1)%m]);
}
s+=2*PI*l;
cout<<(int)(s+0.5)<<endl;
}
return 0;
}
