1185

#include <iostream>
#include <vector>
#include <algorithm>
#include <stack>
#define _USE_MATH_DEFINES
#include <math.h>
using namespace std;

struct coor {
    long long int x, y;
};

long long int rotate(coor a, coor b, coor c) {
    return (b.x - a.x) * (c.y - b.y) - (b.y - a.y) * (c.x - b.x);
}

vector <coor> dots;

int n;
double l;

int main()
{
    cin >> n >> l;

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

        int a, b;
        cin >> a >> b;

        dots.push_back({ a, b });
    }


    int yy = 100000000, ind = -1;;
    for (int i = 0; i < n; i++) {
        if (dots[i].y < yy) {
            yy = dots[i].y;
            ind = i;
        }
    }

    coor beg = dots[ind];
    dots.erase(dots.begin() + ind);

    for (int i = 0; i < n - 1; i++) {
        dots[i].x = dots[i].x - beg.x;
        dots[i].y = dots[i].y - beg.y;
    }

    beg.x = 0; beg.y = 0;

    sort(dots.begin(), dots.end(), [](coor a, coor b) {
        if (a.x * b.y == b.x * a.y) {
            if (a.y == b.y) {
                if (a.x < b.x) {
                    return true;
                }
                else {
                    return false;
                }
            }
            else {
                if (a.y < b.y) {
                    return true;
                }
                else {
                    return false;
                }
            }
        }
        else {
            return (a.x * b.y > b.x * a.y);
        }
    });

    vector <coor> aga;

    aga.push_back(beg);
    aga.push_back(dots[0]);

    for (int i = 1; i < n - 1; i++) {

        while (rotate(aga[aga.size() - 1], dots[i], aga[aga.size() - 2]) < 0) {
            aga.erase(aga.end() - 1);
        }

        aga.push_back(dots[i]);
    }

    while (rotate(aga[aga.size() - 1], beg, aga[aga.size() - 2]) < 0) {
        aga.erase(aga.end() - 1);
    }

    double summ = 0;
    for (int i = 1; i < aga.size(); i++) {
        summ += sqrt(pow(aga[i].x - aga[i - 1].x, 2) + pow(aga[i].y - aga[i - 1].y, 2));
    }

    summ += sqrt(pow(beg.x - aga[aga.size() - 1].x, 2) + pow(beg.y - aga[aga.size() - 1].y, 2));

    summ += 2 * M_PI * l;

    cout << (int) (summ + 0.5);
}