import Foundation

let input:String = readLine()!

let nums:[String] = input.componentsSeparatedByString(" ")

let a = Double(nums[0])!
let b = Double(nums[1])!
let x = Double(nums[2])!
let y = a*b - (x/a)
let w:Double
let atan: Double
let angle:Double

if (a*b)/2 >= y {
  w = 2*y/a
  atan = atan2(w, a)
  angle = atan * 360 / (2 * M_PI)
} else {
  w = 2*y/b - a
  atan = atan2(b, a - w)
  angle = atan * 360 / (2 * M_PI)
}

print(angle)