1 #include<iostream>
 2 #include<stdio.h>
 3 #include<cstring>
 4 #include<cstdlib>
 5 #include<cmath>
 6 #include<algorithm>
 7 using namespace std;
 8 const double pi = acos(-1.0);
 9 
10 struct node
11 {
12     int x,y;
13 };
14 node a[1002],stack1[1002];
15 
16 double dis(node n1,node n2)
17 {
18     return (double)sqrt( (n1.x-n2.x)*(n1.x-n2.x)*1.0 + (n1.y-n2.y)*(n1.y-n2.y)*1.0 );
19 }
20 double cross(node a,node n1,node n2)
21 {
22     return (n1.x-a.x)*(n2.y-a.y) - (n1.y-a.y)*(n2.x-a.x);
23 }
24 bool cmp(node n1,node n2)
25 {
26     double k = cross(a[0],n1,n2);
27     if( k>0) return true;
28     else if( k==0 && dis(a[0],n1)<dis(a[0],n2))
29         return true;
30     else return false;
31 }
32 double  Graham(int n)
33 {
34     int i,head;
35     double r=0;
36     for(i=1;i<n;i++)
37         if(a[i].x<a[0].x ||(a[i].x==a[0].x&&a[i].y<a[0].y ) )
38             swap(a[0],a[i]);
39     sort(a+1,a+n,cmp);
40     a[n]=a[0];
41     stack1[0]=a[0];
42     stack1[1]=a[1];
43     stack1[2]=a[2];
44     head=2;
45     for(i=3;i<=n;i++)
46     {
47         while( head>=2 && cross(stack1[head-1],stack1[head],a[i])<=0 )head--;
48         stack1[++head]=a[i];
49     }
50     for(i=0;i<head;i++)
51     {
52         r=r+dis(stack1[i],stack1[i+1]);
53     }
54     return r;
55 }
56 int main()
57 {
58     int n,L,i;
59     double ans;
60    while(scanf("%d%d",&n,&L)>0)
61     {
62         for(i=0;i<n;i++)
63             scanf("%d%d",&a[i].x,&a[i].y);
64         ans=Graham(n);
65         ans=ans+2*pi*L;
66         printf("%.0lf\n",ans);
67     }
68     return 0;
69 }