//3.141592653
#include <stdio.h>
typedef double d;d p(d x,d y,d X,d Y,int D){d w=X-x,h=Y-y;if(!D)return w*h/2;
else if(X*X+Y*Y<1)return w*h;else if(x*x+y*y>1)return 0;else{w/=2;h/=2;D--;
return p(x,y,x+w,y+h,D)+p(x+w,y,X,y+h,D)+p(x,y+h,x+w,Y,D)+p(x+w,y+h,X,Y,D);}}
main(){printf("%.9f",p(0,0,1,1,24)*4);}