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])!
var y:Double = a*b - (x/a)
var w:Double
var atan: Double
var angle:Double

if (a*b)/2.0 >= y {
  w = 2.0*y/a
  angle = w/a
  atan = atan(angle)
  angle = atan * 360.0 / (2.0 * M_PI)
} else {
  w = 2.0*y/b - a
  angle = b/(a-w)
  atan = atan(angle)
  angle = atan * 360.0 / (2.0 * M_PI)
}

print(angle)
