import java.util.*

fun main(args: Array<String>) {
    val eps = 0.0000001
    val scanner = Scanner(System.`in`)

    val a = scanner.nextInt()
    val b = scanner.nextInt()
    val x = scanner.nextInt()

    val m = a * a * b
    val space = m - x

    var l = 0.0
    var r = 90.0
    while (l + eps < r) {
        val mid = (l + r) / 2.0
        val rad = Math.toRadians(mid)
        val d = a * Math.tan(rad)
        if (d < b) {
            val s = a * a * d / 2.0
            if (s > space) {
                r = mid
            } else {
                l = mid
            }
        } else {
            val d2 = b / Math.tan(rad)
            val s = m - a * d2 * b / 2.0
            if (s > space) {
                r = mid
            } else {
                l = mid
            }
        }
    }

    println(l)
}