import java.lang.Math.PI
import java.lang.Math.atan

fun main(args: Array<String>) {
    var (a,b,x) = readLine()!!.split(" ").map { it.toDouble() }
    var xHeight = x / (a * a)
    if (a * a * b / 2 > x){
        println(90 - atan(2 * a * xHeight / (b * b)) * 180 / PI)
    }else{
        println(90 - atan(a / (2 * (b - xHeight))) * 180 / PI )
    }
}