double n,r,l[2000];

double f(double r,double a,double b){
       if(a<0)a=0;
       if(b<0)b=0;
       if(a+b<=r)return 0;
       if(a>=r+b)return b*b*PI;
       if(b>=r+a)return a*a*PI;
       double ta=acos((r*r+a*a-b*b)/(r*a*2));
       double tb=acos((r*r+b*b-a*a)/(r*b*2));
       return a*a*(ta-sin(2*ta)/2)+b*b*(tb-sin(2*tb)/2);
}

{
	rd(n,r,l(n+1));
	int am,as,bm,bs;
	as=0;
	bs=sum(l(n+1));
	rep(i,1,n+1){
		am=max[k=0---i-1](l[k]);
		bm=max[k=i---n](l[k]);
		as+=l[i-1];
		bs-=l[i-1];
		wt(f(r,as,bs)-f(r,as,bm*2-bs)-f(r,am*2-as,bs)+f(r,am*2-as,bm*2-bs));
	}
}