program water_bottle
    implicit none
    integer(8):: a, b, x
    read*, a,b,x
    if (x*2 < a*a*b) then
        print*, 180d0/acos(-1d0)*atan((dble(a*b*b))/dble(2*x))
    else
        print*, 180d0/acos(-1d0)*atan(dble(2*(a*a*b-x))/dble(a*a*a))
    end if
end program water_bottle