#include<stdio.h>
#include<algorithm>
#include<math.h>
using namespace std;
#define PI 3.14159265359
int n, R, st[1010], top, P[1010];
double Res;
struct point{
int x, y;
bool operator <(const point &p)const{
return x != p.x ? x < p.x : y < p.y;
}
}w[1010];
int ccw(point a, point b, point c){
return (b.x - a.x)*(c.y - a.y) - (b.y - a.y)*(c.x - a.x);
}
double dist(point a, point b){
double D = (b.x - a.x)*(b.x - a.x) + (b.y - a.y) * (b.y - a.y);
return sqrt(D);
}
int main()
{
int i, cnt = 0;
scanf("%d%d", &n, &R);
for (i = 0; i < n; i++){
scanf("%d%d", &w[i].x, &w[i].y);
}
sort(w, w + n);
st[++top] = 0;
for (i = 1; i < n; i++){
while (top > 1 && ccw(w[st[top - 1]], w[st[top]], w[i]) <= 0)top--;
st[++top] = i;
}
for (i = 1; i < top; i++)P[++cnt] = st[i];
top = 0;
st[++top] = 0;
for (i = 1; i < n; i++){
while (top > 1 && ccw(w[st[top - 1]], w[st[top]], w[i]) >= 0)top--;
st[++top] = i;
}
for (i = top; i > 1; i--)P[++cnt] = st[i];
P[cnt + 1] = P[1];
for (i = 1; i <= cnt; i++){
Res += dist(w[P[i + 1]], w[P[i]]);
}
printf("%.11lf\n", Res + PI * 2.0 * R);
}
