#include <bits/stdc++.h>
using namespace std;
#define ldb double
#define pb push_back
#define mp make_pair

struct pt{
	ldb x,y;

	pt():x(0),y(0){}
	pt(ldb a,ldb b):x(a),y(b){}
};

pt operator - (pt a,pt b){return pt(a.x-b.x,a.y-b.y);}
pt operator - (pt a){return pt(-a.x,-a.y);}
pt operator + (pt a,pt b){return pt(a.x+b.x,a.y+b.y);}
pt operator * (pt a,ldb b){return pt(a.x*b,a.y*b);}
pt operator / (pt a,ldb b){return pt(a.x/b,a.y/b);}

pt perp(pt a){return pt(-a.y,a.x);}
ldb cross(pt a,pt b){return a.x*b.y-a.y*b.x;}
ldb dot(pt a,pt b){return a.x*b.x+a.y*b.y;}
ldb abs(pt a){return sqrt(dot(a,a));}

int part(pt a){return a.y<0 || (a.y==0 && a.x<0);}

bool operator < (pt a,pt b){return tie(a.x,a.y)<tie(b.x,b.y);}

const int N=10050;
pt pts[N];
vector<pt> ConvexHull(int n){
	sort(pts+1,pts+1+n);
	vector<pt> hull;
	int sz=0;
	for(int t=0;t<2;t++){
		int was=sz;
		for(int i=1;i<=n;i++){
			while(sz>was+1 && cross(hull[sz-1]-hull[sz-2],pts[i]-hull[sz-2])<=0){
				hull.pop_back();
				sz--;
			}
			hull.pb(pts[i]);
			sz++;
		}
		hull.pop_back();
		sz--;
		reverse(pts+1,pts+1+n);
	}
	return hull;
}

void Inter(pt a,pt b,ldb r,vector<pt>& cand){
	pt v=b-a;
	ldb d=cross(v,a)/abs(v);
	pt h=-perp(v);
	h=h/abs(h)*d;
	ldb len=sqrt(max(0.0,r*r-d*d));
	cand.pb(h+v/abs(v)*len);
	cand.pb(h-v/abs(v)*len);
}

int main(){
	int n,r;
	scanf("%i %i",&n,&r);
	for(int i=1;i<=n;i++){
		int x,y;
		scanf("%i %i",&x,&y);
		pts[i]=pt(x,y);
	}
	vector<pt> hull=ConvexHull(n);
	if(hull.size()<2){
		printf("0.0\n");
		return 0;
	}
	vector<pt> cand;
	for(int i=0;i<hull.size();i++){
		Inter(hull[i],hull[(i+1)%hull.size()],r,cand);
		Inter(pt(0,0),perp(hull[i]-hull[(i+1)%hull.size()]),r,cand);
	}
	//printf("Hull ");
	//for(pt p:hull)printf("(%lf, %lf) ",p.x,p.y);
	//printf("\n");
	sort(cand.begin(),cand.end(),[&](pt a,pt b){return mp(part(a),0.0)<mp(part(b),cross(a,b));});
	int L=0,R=0;
	auto nxt=[&](int x){return (x+1)%hull.size();};
	auto pre=[&](int x){return (x-1+hull.size())%hull.size();};
	ldb ans=0;
	for(int i=0;i<hull.size();i++){
		ans+=cross(hull[i],hull[nxt(i)]);
	}
	ans=abs(ans)/2;
	for(pt p:cand){
		//printf("(%lf, %lf)\n",p.x,p.y);
		while(cross(hull[L]-p,hull[nxt(L)]-p)<0)L=nxt(L);
		while(cross(hull[L]-p,hull[pre(L)]-p)<0)L=pre(L);
		while(cross(hull[R]-p,hull[nxt(R)]-p)>0)R=nxt(R);
		while(cross(hull[R]-p,hull[pre(R)]-p)>0)R=pre(R);
		//printf("L(%lf, %lf) R(%lf, %lf)\n",hull[L].x,hull[L].y,hull[R].x,hull[R].y);
		ldb now=0;
		for(int i=L;i!=R;i=nxt(i)){
			now+=cross(hull[i],hull[nxt(i)]);
		}
		now+=cross(hull[R],p);
		now+=cross(p,hull[L]);
		now=abs(now)/2;
		//printf("%lf\n",now);
		ans=max(ans,now);
	}
	printf("%.12lf\n",ans);
	return 0;
}