var y,x,r:longint; q,z:int64; Begin ReadLn(r); z:=0; y:=0; x:=r; q:=Sqr(r); Repeat While (Sqr(x)+Sqr(y)>q) and (x<0) do Dec(x); Inc(z,x); y:=y+1; Until y>r; z:=z*4; WriteLn(z); End.