open System

let a,b,x=stdin.ReadLine().Split()|>Array.map double|>fun c -> double c.[0],double c.[1],double c.[2]
[<EntryPoint>]
let main argv =
    let f r = r*180.0/Math.PI
    let V =a*a*b
    if x>=(V/2.0) then atan (2.0*((a*a*b)-x)/(a*a*a)) else atan ((a*b*b)/(2.0*x))
    |>f
    |>stdout.WriteLine
    0