#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>using namespace std;const int MAXN=1050;int n,l;int st[MAXN],stop,cnt;int ans[MAXN];struct point{	int x,y;}p[MAXN];bool cmp(point A,point B){	if(A.y<B.y) return true;	else if(A.y==B.y){		if(A.x<B.x) return true;	}	return false;}bool multi(point a,point b,point c){	return (a.x-c.x)*(b.y-c.y)-(a.y-c.y)*(b.x-c.x)>0;}void slove(){	stop=0; cnt=0;	st[stop++]=0; st[stop++]=1;	for(int i=2;i<n;i++){		while(stop>1&&multi(p[st[stop-1]],p[i],p[st[stop-2]])) stop--;		st[stop++]=i;	}	for(int i=0;i<stop;i++){		ans[cnt++]=st[i];	}	stop=0;	st[stop++]=n-1; st[stop++]=n-2;	for(int i=n-3;i>=0;i--){		while(stop>1&&multi(p[st[stop-1]],p[i],p[st[stop-2]])) stop--;		st[stop++]=i;	}	for(int i=0;i<stop;i++)	ans[cnt++]=st[i];}double dist(point a,point b){	return sqrt((a.x-b.x)*(a.x-b.x)*1.0+(a.y-b.y)*(a.y-b.y)*1.0);}int main(){	while(scanf("%d%d",&n,&l)!=EOF){		for(int i=0;i<n;i++){			scanf("%d%d",&p[i].x,&p[i].y);		}		sort(p,p+n,cmp);		slove();		double anl=4*acos(0.0)*l;		for(int i=1;i<cnt;i++){			anl+=dist(p[ans[i-1]],p[ans[i]]);		}		printf("%.0lf\n",anl);	}	return 0;}