#include <cstdio>

#include <algorithm>

#include <cmath>

#include <vector>

using namespace std;

double EPS=1e-10;

const double PI=acos(-1.0);

double add(double a,double b){

    if(abs(a+b)<EPS*(abs(a)+abs(b)))return 0;

    return a+b;

}

struct P{

    double x,y;

    P(){}

    P(double x,double y):x(x),y(y){}

    P operator + (P p){return P(add(x,p.x),add(y,p.y));}

    P operator - (P p){return P(add(x,-p.x),add(y,-p.y));}

    P operator * (double d){return P(x*d,y*d);}

    double dot(P p){return add(x*p.x,y*p.y);} //点积

    double det(P p){return add(x*p.y,-y*p.x);}  //叉积

};

bool cmp_x(const P& p,const P& q){

    if(p.x!=q.x)return p.x<q.x;

    return p.y<q.y;

}

vector<P> convex_hull(P* ps,int n){

    sort(ps,ps+n,cmp_x);

    int k=0;

    vector<P> qs(n*2);

    for(int i=0;i<n;i++){

        while((k>1)&&(qs[k-1]-qs[k-2]).det(ps[i]-qs[k-1])<=0)k--;

        qs[k++]=ps[i];

    }

    for(int i=n-2,t=k;i>=0;i--){

        while(k>t&&(qs[k-1]-qs[k-2]).det(ps[i]-qs[k-1])<=0)k--;

        qs[k++]=ps[i];

    }qs.resize(k-1);

    return qs;

}

double dist(P p,P q){return sqrt((p-q).dot(p-q));}

const int MAX_N=1000;

int N,L;

P ps[MAX_N];

vector<P> con;

void solve(){

    for(int i=0;i<N;i++)scanf("%lf%lf",&ps[i].x,&ps[i].y);

    con=convex_hull(ps,N);

    double res=0;

    for(int i=0;i<con.size()-1;i++)res+=dist(con[i],con[i+1]);

    res+=dist(con[0],con[con.size()-1]);

    res+=2*PI*L;

    printf("%d\n",(int)(res+0.5));

}

int main(){

    while(~scanf("%d%d",&N,&L))solve();

    return 0;

}