//#include<bits/stdc++.h>
#include<iostream>
#include<cmath>
#include<algorithm>
#define fi first
#define se second
#define INF 0x3f3f3f3f
#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define pqueue priority_queue
#define NEW(a,b) memset(a,b,sizeof(a))
#define lowbit(x) ((x)&(-x))
using namespace std;
const double pi=4.0*atan(1.0);
const double e=exp(1.0);
const int maxn=4e4+8;
typedef long long LL;
typedef unsigned long long ULL;
const LL mod=1e9+7;
const ULL base=1e7+7;
struct Point{int x,y;bool operator<(Point &u){//坐标排序if(x!=u.x) return x<u.x;return y<u.y;}
};
Point vex[maxn],Stack[maxn],Basis;
short checkL(Point p,Point q,Point s){//判断点s是否在直线pq的左侧int area2=p.x*q.y-p.y*q.x+q.x*s.y-q.y*s.x+s.x*p.y-s.y*p.x;if(area2>0) return 1;//表示在左侧if(area2==0) return 0;//表示在同一条线上；return -1;//表示在右侧
}
double dis(Point u,Point v){//计算uv的距离return sqrt((u.x-v.x)*(u.x-v.x)*1.0+(u.y-v.y)*(u.y-v.y));
}
bool cmp(Point a,Point b){//极角排序short m=checkL(Basis,a,b);if(m==1) return 1;//b在基点与a的连线的左侧，说明b的极角大于aif(m==0&&dis(Basis,a)<=dis(Basis,b))//极角相同时，靠近基点的排在前return 1;return 0;
}
int main(){cin.tie(0);cout.tie(0);int n,l;cin>>n>>l;for(int i=0;i<n;i++){cin>>vex[i].x>>vex[i].y;}sort(vex,vex+n);Basis=vex[0];//选第一个点为基点sort(vex+1,vex+n,cmp);int top=0;Stack[top]=vex[0];Stack[++top]=vex[1];for(int i=2;i<n;i++){while(top>=1&&checkL(Stack[top-1],Stack[top],vex[i])<0){top--;}Stack[++top]=vex[i];}double sum=0.0;for(int i=0;i<top;i++){sum+=dis(Stack[i],Stack[i+1]);}sum+=dis(Stack[top],Stack[0]);sum+=2.0*pi*l;LL ans=(LL)sum;if(sum-(double)ans>=0.5){ans++;}cout<<ans<<endl;system("pause");return 0;
}