struct POINT{

    double x,y;

    POINT(double _x = , double _y = ):x(_x),y(_y){};

};

POINT p[MAXN],s[MAXN];

double dist(POINT p1,POINT p2){

    return(sqrt((p1.x-p2.x) * (p1.x-p2.x) + (p1.y-p2.y) * (p1.y-p2.y)));

}

double multiply(POINT sp,POINT ep,POINT op){

    return (sp.x-op.x) * (ep.y-op.y) - (ep.x-op.x) * (sp.y-op.y);

}

bool ptcmp(POINT a,POINT b){    // 极角排序cmp p[]为全局变量

    if(multiply(a,b,p[]) == ) return dist(p[],a) < dist(p[],b);

    return (multiply(a,b,p[]) > );

}

int Graham_scan(POINT p[],POINT s[],int n){ //  返回凸包点的个数

    int i,k = ,top = ;

    for(i = ; i < n ; i++)     //  取y最小且x最小的点为凸包起点

        if((p[i].y < p[k].y) || ((p[i].y == p[k].y) && (p[i].x < p[k].x)))

            k = i;

    swap(p[],p[k]);            //  起点设置为p[0]

    sort(p+,p+n,ptcmp);        //  极角排序

    for(i =  ; i <  ; i++)

        s[i] = p[i];            //  前三个点入栈

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

        while(multiply(p[i],s[top],s[top-]) >= )

            top--;

        s[++top] = p[i];

    }

    return top + ;

}

int main()

{

    int a,b,n;

    double r;

    while(~scanf("%d%lf",&n,&r)){

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

            scanf("%lf%lf",&p[i].x,&p[i].y);

        int len = Graham_scan(p,s,n);

        double sum = dist(s[len-],s[]);

        for(int i =  ; i < len- ; i++){

            sum += dist(s[i],s[i+]);

        }

        sum += (PI*r*);

        cout<<floor(sum+0.5)<<endl;

    }

    return ;

}