1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<algorithm>
 5 using namespace std;
 6 #define pi acos(-1)
 7 #define eps 1e-8
 8 using namespace std;
 9 const int N=1005;
10 struct point{
11     double x,y;
12 }pt[N];
13 int con[N];
14 int n,l,tot;
15 double dist(point a,point b){
16     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
17 }
18 double xmult(point p0,point p1,point p2){
19     double x1=p1.x-p0.x;
20     double y1=p1.y-p0.y;
21     double x2=p2.x-p0.x;
22     double y2=p2.y-p0.y;
23     return (x1*y2-x2*y1);
24 }
25 bool cmp(point a,point b){
26     if(xmult(pt[0],a,b)>0||xmult(pt[0],a,b)==0&&(dist(a,pt[0])<dist(b,pt[0])))return true;
27     return false;
28 }
29 void graham(){
30     sort(pt+1,pt+n,cmp);
31     tot=0;
32     con[tot++]=0;
33     con[tot++]=1;
34     for(int i=2;i<n;){
35         if(tot<1||xmult(pt[con[tot-2]],pt[con[tot-1]],pt[i])>=0)
36             con[tot++]=i++;
37         else tot--;
38     }
39     con[tot]=0;
40 }
41 int main()
42 {
43     //freopen("in.txt","r",stdin);
44     int i,k;
45     double ans;
46     while(scanf("%d %d",&n,&l)!=EOF){
47         k=n-1;
48         for(i=n-1;i>=0;i--){
49             scanf("%lf %lf",&pt[i].x,&pt[i].y);
50             if(pt[i].y<pt[k].y||((pt[i].y==pt[k].y)&&(pt[i].x<pt[k].x)))
51                     k=i;
52         }
53         if(k){
54             swap(pt[0].x,pt[k].x);
55             swap(pt[0].y,pt[k].y);
56         }
57         graham();
58         ans=0;
59         for(i=0;i<tot;i++)
60             ans+=dist(pt[con[i]],pt[con[i+1]]);
61         ans+=2*pi*l;
62         printf("%d\n",(int)(ans+0.5));
63     }
64     return 0;
65 }