#include <bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
using namespace std;

typedef vector<int>vi;
#define fi first
#define se second
#define mkp make_pair
typedef pair<int,int>pii;
#define pb push_back

#define maxn 400005
#define inf 0x3f3f3f3f

mt19937_64 rnd(64);
#define db double
const db eps=1e-8,pi=3.14159265358979323;
int sgn(db x){
    return x<-eps?-1:x>eps;
}
int cmp(db a,db b){
    return sgn(a-b);
}
struct P{
    db x,y;
    int id;
    P(db xx=0,db yy=0){
        x=xx,y=yy;
    }
    P&operator +=(P o){return x+=o.x,y+=o.y,*this;}
    P&operator -=(P o){return x-=o.x,y-=o.y,*this;}
    P&operator *=(db o){return x*=o,y*=o,*this;}
    P&operator /=(db o){return x/=o,y/=o,*this;}

    friend P operator +(P a,P b){return a+=b;}
    friend P operator -(P a,P b){return a-=b;}
    friend P operator *(P a,db b){return a*=b;}
    friend P operator /(P a,db b){return a/=b;}

    friend db operator *(P a,P b){
        return a.x*b.y-a.y*b.x;
    }
    friend db operator %(P a,P b){
        return a.x*b.x+a.y*b.y;
    }
    P rot90(){
        swap(x,y),x=-x;
        return *this;
    }

    db len(){
        return sqrt(x*x+y*y);
    }
    db len2(){
        return x*x+y*y;
    }

    void print(){
        cout<<"("<<x<<","<<y<<")\n";
    }
};
db dis(P a,P b){
    return ((a-b)).len();
}
db cross(P a,P b,P c){
    return (b-a)*(c-a);
}

struct L{
    P a,b;
    int id;
    L(P aa,P bb){
        a=aa,b=bb;
        id=-1;
    }
    int in_sgn(P p){
        return sgn((b-a)*(p-a));
    }
    void print(){
        cout<<"("<<a.x<<","<<a.y<<")--("<<b.x<<","<<b.y<<")  "<<id<<"\n";
    }
};
P interl(P p1,P p2,P q1,P q2){
    db s1=cross(q1,q2,p1);
    db s2=-cross(q1,q2,p2);
    return (p1*s2+p2*s1)/(s1+s2);
}

P operator &(L a,L b){
    return interl(a.a,a.b,b.a,b.b);
}
int chksgn(L a,L b,L c){
    return c.in_sgn(a&b);
}
vector<L>cut(vector<L>&a,L l){
    vector<L>b;
    int n=a.size();
    For(i,0,n-1){
        L a1=a[i],a2=a[(i+1)%n],a3=a[(i+2)%n];
        int d1=chksgn(a1,a2,l);
        int d2=chksgn(a2,a3,l);
        if(d1>0 || d2>0 || (d1==0 && d2==0))b.pb(a2);
        if(d1>=0 && d2<0) b.pb(l);
    }
    return b;
}
L bisec(P a,P b){
    P o=(a+b)*0.5;
    return L(o,o+((b-a).rot90()));
}
vector<vector<L> > vor(vector<P>a){
    int n=a.size();
    auto b=a;
    const db U=1e5;
    vector<L>all;
    all.pb(L(P(-U,-U),P(U,-U)));
    all.pb(L(P(U,-U),P(U,U)));
    all.pb(L(P(U,U),P(-U,U)));
    all.pb(L(P(-U,U),P(-U,-U)));
    vector<vector<L> > res;
    For(i,0,n-1) res.pb(all);
    For(i,0,n-1){
        for(auto x:b){
            if(dis(x,a[i])>eps){
                L tmp=bisec(a[i],x);
                tmp.id=x.id;
             //   cout<<"cut "<<i<<" "<<x.id<<"\n";
             //   tmp.print();
                res[i]=cut(res[i],tmp);
            }
        }
    }
    return res;
}


struct cir{
    P o;
    db r;
    cir(P oo=P(0,0),db rr=0.0){
        o=oo,r=rr;
    }
};

db rad(P a,P b){
    return atan2l(a*b,a%b);
}

vector<P>operator &(cir a,L b){
    if(cmp(abs(((a.o-b.a)*(b.b-b.a))/dis(b.a,b.b)),a.r)>0) return {};
	db x=(b.a-a.o)%(b.b-b.a);
	db y=(b.b-b.a).len2();
	db d=x*x-y*((b.a-a.o).len2()-a.r*a.r);
	d=max(d,(db)0.0);
	P m=b.a-(b.b-b.a)*(x/y);
	P dr=(b.b-b.a)*(sqrt(d)/y);
	return {m-dr,m+dr};
}

db areaCT(db r,P p1,P p2){
	vector<P>is=(cir(P(0,0),r)&(L(p1,p2)));
	if(!is.size()) return r*r*rad(p1,p2)/2;
	bool b1=(cmp(p1.len2(),r*r)>0), b2=(cmp(p2.len2(),r*r)>0);
	if(b1&&b2){
		if(sgn((p1-is[0])%(p2-is[0]))<=0) 
			return (r*r*(rad(p1,is[0])+rad(is[1],p2))+(is[0]*is[1]))/2;
		return r*r*rad(p1,p2)/2;
	}
	if(b1) return (r*r*rad(p1,is[0])+is[0]*p2)/2;
	if(b2) return (p1*is[1]+r*r*rad(is[1],p2))/2;
	return (p1*p2)/2;
}

db solve(cir t,vector<P>a){
    db res=0;
    For(i,0,(int)a.size()-1){
        res+=areaCT(t.r,(a[i]-t.o),(a[(i+1)%a.size()]-t.o));
    }
    return res;
}

int n;
db k;
vector<P>a;

db res;

signed main()
{
//    P p=P(1,1);
//    p=p*0.5;
//    p.print();
    cin>>n>>k;
    a.resize(n);
    For(i,0,n-1)cin>>a[i].x>>a[i].y;
    shuffle(a.begin(),a.end(),rnd);
    For(i,0,n-1) a[i].id=i;
    vector<vector<L> > vd=vor(a);
 //   cout<<"QAQ\n"; return 0;
    For(i,0,n-1){
        auto v=vd[i];
        int m=v.size();
        For(qwq,0,m-1){

            int u=v[qwq].id;
          //  v[qwq].print();

            if(u==i || u<0) continue;
            // (i,u)
         //   cout<<"work "<<i<<" "<<u<<"\n";
            auto g=v;
            For(k,0,n-1)
                if(k!=i && k!=u){
                    L tmp=bisec(a[u],a[k]);
                    g=cut(g,tmp);
                }
            if(!g.size()) continue;

            db ds=dis(a[i],a[u]);
            if(ds>=k) continue;

            P o=(a[i]+a[u])*0.5;

            db A = k/2;
            P dx=(a[u]-a[i])/ds*A;
            P ddy=dx,dy=P(0,0);
            ddy.rot90();
            
            db rat=0;
			
			db leny=sqrt((k/2)*(k/2)-(ds/2)*(ds/2));
			dy=ddy/ddy.len()*leny;
		//	cout<<dy.x<<" "<<dy.y<<"\n";
			
        //    dx.print();
       //     dy.print();

            rat=dx.len()/dy.len();
            cir cr;
            cr.o=P(0,0);
            cr.r=dy.len();
            
            dx/=dx.len();
            dy/=dy.len();
          //  cout<<"rat "<<rat<<"\n";
          //  cout<<"dx: ";dx.print();
          //  cout<<"dy: ";dy.print();
            
            vector<P>cv;
           // cout<<"cir "<<dy.len()<<"\n";
            For(k,0,(int)g.size()-1) {
                P p=(g[k]&g[(k+1)%g.size()]);
           //     cout<<"p: "<<p.x<<" "<<p.y<<"\n";
                p=p-o;
                P t=P(p%dx,p%dy);
                t.x/=rat;
           //     cout<<"t: "<<t.x<<" "<<t.y<<"\n";
                cv.pb(t);
            }
            
            db ans=solve(cr,cv);
            res+=ans*rat;
         //   cout<<"ans "<<(ans*rat)<<"\n";
        }
    }
    printf("%.12lf",res);
	return 0;
}

/*
3 10
0 0
0 5
5 5

5 75
0 0
170 0
140 30
60 30
0 70
*/