#pragma GCC optimize("O3,unroll-loops")
#include<bits/stdc++.h>
using namespace std;
const int inf = 1e9 + 7;
typedef long long LL;
typedef unsigned long long ULL;
#define all(x) ((x).begin()), ((x).end())
#define pb push_back
typedef double D;
struct P {
    D x, y;
    void print() const{
        printf("%.6f %.6f\n", x, y);
    }
    P operator + (const P & b) const { return P{x + b.x, y + b.y}; }
    P operator - (const P & b) const { return P{x - b.x, y - b.y}; }
    D operator * (const P & b) const {
        return x * b.y - y * b.x;
    }
    bool operator < (const P & b) const {
        return x < b.x || x == b.x && y < b.y;
    }
    void scan() {
        scanf("%lf%lf", &x, &y);
    }
    P rev() const {
        return P{-y, x};
    }
    D sqrlen() const {
        return x * x + y * y;
    }
    D len() const {
        return sqrt(max((D)0., sqrlen()));
    }
    P zoom(const D & l) const {
        D lambda = l / len();
        return P{lambda * x, lambda * y};
    }
};
const int N = 10011;
P a[N];
P operator * (const D & x, const P & b) { return P{x * b.x, x * b.y}; }
struct L {
    P s, d;
    bool contains(const P & x) {
        return d * (x - s) > 0;
    }
    void print() const {
        printf("---\n");
        s.print();
        d.print();
        printf("----\n");
    }
};
P intersect(const L & a, const L & b) {
    D lambda = (b.s - a.s) * b.d / (a.d * b.d);
    return a.s + lambda * a.d;
}
D sum[N * 2];
struct Rec {
    P p;
    int id;
    int side;
};
bool operator < (const Rec & a, const Rec & b) {
    int da = a.p < P{0, 0};
    int db = b.p < P{0, 0};
    if(da != db) {
        return da < db;
    } else {
        return a.p * b.p > 0;
    }
}
P intersect(const P & a, const P & b, const D & r) {
    P i = intersect(L{a, b - a}, L{P{0, 0}, (b - a).rev()});
    D len = sqrt(r * r - i.sqrlen());
    return i + (b - a).zoom(len);
}
int main() {
    int n, r;
    scanf("%d%d", &n, &r);
    for(int i = 0; i < n; i++) {
        a[i].scan();
    }
    sort(a, a + n);
    vector<P> vec;
    for(int i = 0; i < n; i++) {
        while(vec.size() >= 2 && (a[i] - vec.back()) * (vec.back() - vec[vec.size() - 2]) >= -0.5) {
            vec.pop_back();
        }
        vec.push_back(a[i]);
    }
    int siz = vec.size();
    for(int i = n - 1; i >= 0; i--) {
        while(vec.size() >= siz + 1 && (a[i] - vec.back()) * (vec.back() - vec[vec.size() - 2]) >= -0.5) {
            vec.pop_back();
        }
        vec.push_back(a[i]);
    }
    vec.pop_back();
    /*for(int i =0 ; i  < (int)vec.size(); i++) {
        printf("vec[%d] = ", i);
        vec[i].print();
    }*/
    D ans = 0;
    if(vec.size() == 1) {
        printf("0\n");
        exit(0);
    }
    for(int i = 1; i <= (int)vec.size() * 2; i++) {
        
        sum[i] = sum[i - 1] + (vec[(i - 1) % (int)vec.size()] * vec[i % (int)vec.size()]);
    }
    auto update = [&](int x, int y) {
        if(x == y) {
            return;
        }
        D area = sum[x < y ? x + (int)vec.size() : x] - sum[y];
        P p = (vec[x] - vec[y]).rev().zoom(r);
        area += vec[x] * p + p * vec[y];
        area = abs(area) / 2;
        //printf("update %d %d %.6f\n", x, y, area);
        ans = max(ans, area);
    };
    update(0, 1);
    update(1, 0);
    vector<Rec> events;
    for(int i = 0; i < (int)vec.size(); i++) {
        P a = vec[i], b = vec[(i + 1) % (int)vec.size()];
        events.pb({intersect(a, b, r), (i + 1) % (int)vec.size(), 0});
        events.pb({intersect(b, a, r), (i + 1) % (int)vec.size(), 1});
        //printf("%d %d ", events[events.size() - 2].id, events[events.size() - 2].side);
        //events[events.size() - 2].p.print();
        //printf("%d %d ", events[events.size() - 1].id, events[events.size() - 1].side);
        //events[events.size() - 1].p.print();
    }
    int le = -1, ri = -1;
    sort(all(events));
    //printf("---\n");
    for(int i = 0; i < (int)events.size(); i++) {
        if(events[i].side == 0) {
            le = events[i].id;
        } else {
            ri = events[i].id;
        }
        //printf("%d %d ", events[i].id, events[i].side);
        //events[i].p.print();
    }
    update(le, ri);
    for(int i = 0; i < (int)events.size(); i++) {
        if(events[i].side == 0) {
            le = events[i].id;
        } else {
            ri = events[i].id;
        }
        update(le, ri);
    }
    printf("%.12f\n", ans);
}