#include<bits/stdc++.h>
#ifdef xay5421
#define D(...) fprintf(stderr,__VA_ARGS__)
#else
#define D(...) ((void)0)
#endif
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)
#define SZ(x) ((int)(x).size())
#define pb push_back
using namespace std;
#define N 10005
struct Vec
{
	double x,y;
	Vec(double a=0,double b=0) {x=a,y=b;}
};
const double eps=1e-7;
int sgn(double x)
{
	if(x>eps) return 1;
	else if(x<-eps) return -1;
	return 0;
}
Vec operator + (const Vec &x,const Vec &y) {return Vec(x.x+y.x,x.y+y.y);}
Vec operator - (const Vec &x,const Vec &y) {return Vec(x.x-y.x,x.y-y.y);}
double cdot(const Vec &x,const Vec &y) {return x.x+y.x+x.y*y.y;}
double cross(const Vec &x,const Vec &y) {return x.x*y.y-x.y*y.x;}
double dis(const Vec &x) {return sqrt(x.x*x.x+x.y*x.y);}
int ccw(const Vec &x,const Vec &y,const Vec &z)
{
	int w=sgn(cross(y-x,z-x));
	return w;
}
Vec a[N];
int n,st[N+N],tp;
double ans,R;
int main(){
#ifdef xay5421
	freopen("a.in","r",stdin);
#endif
	cin>>n>>R;
	for(int i=1;i<=n;i++) scanf("%lf %lf",&a[i].x,&a[i].y);
	int mnx=1;
	for(int i=1;i<=n;i++)
	{
		if(a[i].x<a[mnx].x) mnx=i;
	}
	swap(a[mnx],a[1]);
	sort(a+2,a+n+1,[&](const Vec &x,const Vec &y){
		return ccw(a[1],x,y)==-1||(ccw(a[1],x,y)==0&&dis(x-a[1])<dis(y-a[1]));
	});
	st[++tp]=1;
	for(int i=2;i<=n;i++)
	{
		while(tp>=2&&ccw(a[st[tp-1]],a[st[tp]],a[i])>=0) tp--;
		st[++tp]=i;
	}
	for(int i=1;i<=tp;i++) st[i+tp]=st[i];
	double S=0;
	for(int i=2;i<tp;i++) S+=cross(a[st[i+1]]-a[1],a[st[i]]-a[1]);
	S/=2;
//	for(int i=1;i<=tp;i++) printf("%lf %lf\n",a[st[i]].x,a[st[i]].y);
	for(int i=1;i<=tp;i++)
	{
		double siz=0;
		for(int j=i+1;j<i+tp;j++)
		{
			if(j!=i+1) siz+=cross(a[st[j]]-a[st[i]],a[st[j-1]]-a[st[i]])/2;
			double L=dis(a[st[i]]-a[st[j]]);
			double gv=R*L+cross(a[st[i]],a[st[j]]); gv/=2;
			ans=max(ans,S-siz+gv);
//			printf("%d %d : %lf %lf %lf\n",i,j,S,siz,gv);
		}
	}
	printf("%.10lf\n",ans);
	return 0;
}
/*
-1000.000000 0.000000
1000.000000 0.000000
0.000000 -1000.000000
1 2 : 1000000.000000 0.000000 1000000.000000
1 3 : 1000000.000000 1000000.000000 1207106.781187
2 3 : 1000000.000000 0.000000 207106.781187
2 4 : 1000000.000000 500000.000000 1000000.000000
3 4 : 1000000.000000 0.000000 207106.781187
3 5 : 1000000.000000 0.000000 1207106.781187
2207106.7811865476
*/