import java.util.*;import java.math.*;import java.io.*;publicclassMain{staticclassSolution{voidinit(){int R =2;double pi =3.14159265358979;double d = Math.sqrt(7);double S1 =0.5* d *1.5;double A = Math.acos(3.0/4.0);double ang = pi/2.0-2*A;double S2 =0.5* ang * R*R;
System.out.printf("%.2f", S1*4+S2*4);}}publicstaticvoidmain(String[] args)throws IOException {
Solution s =newSolution();
s.init();}}