int n;
double r,l[2000],a,b,c,d;

double f(double a,double b){
	if(a<0)a=0;
	if(b<0)b=0;
	if(a+b<=r)return 0;
	if(b+r<=a)return b*b*PI;
	if(a+r<=b)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));
	b=sum(l(n+1));
	rep(i,n){
		a+=l[i];
		b-=l[i];
		c=max[k=0---i](l[k])*2-a;
		d=max[k=i+1---n](l[k])*2-b;
		wt(f(a,b)-f(a,d)-f(c,b)+f(c,d));
	}
}