#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;
const double PI = acos(0.0)*2;
typedef pair<int, int> point;
#define X first
#define Y second
int n, r;
vector<point> points;
int ccw(point p, point a, point b) {
point u(a.X-p.X, a.Y-p.Y), v(b.X-p.X, b.Y-p.Y);
return u.X * v.Y - u.Y * v.X;
}
double dist(point a, point b) {
return hypot(a.X-b.X, a.Y-b.Y);
}
int main() {
scanf("%d%d", &n, &r);
for (int i=0; i<n; ++i) {
int x, y;
scanf("%d%d", &x, &y);
points.emplace_back(x, y);
}
point pivot = *min_element(points.begin(), points.end());
vector<point> hull;
hull.push_back(pivot);
double ans = 0;
while(1) {
point ph = hull.back(), next = points[0];
for (int i=1; i<points.size(); ++i) {
int cross = ccw(ph, next, points[i]);
if (cross > 0 || (cross == 0 && dist(next, ph) < dist(points[i], ph)))
next = points[i];
}
ans += dist(ph, next);
if (next == pivot) break;
hull.push_back(next);
}
ans += 2*PI*r;
printf("%.10f\n", ans);
return 0;
}
