      PROGRAM WaterBottle
      IMPLICIT NONE
      integer,parameter :: prec = 8
      real(prec) :: a,b,x,ans
      
      read*,a,b,x
      
      x = x / a
      if( x<=a*b/2. )then
        a = 2.*x/b
    !    print*,'before'
    !    print*,a
        
        ans = asin( b/sqrt(a**2.+b**2.) )
      else
        b = 2.*b - 2.*x/a
     !   print*,'after'
        
        ans = asin( b/sqrt(a**2.+b**2.) )
      end if
      
      
      print*,ans/(2._prec*3.1415926535897932_prec)*360._prec
      
      stop
    !  print*,a,b,x
      
      END PROGRAM