import java.lang.Math

fun main(args: Array<String>) {
    var (a,b,x) = readLine()!!.split(" ").map(String::toDouble)
    var s = x / a
    var ans = 0.0
    var la = 0.0
    if (s > b * a / 2) {
        val ub = 2 * s / a - b
        s -= a * ub
        b -= ub
        la = a
    } else {
        la = 2 * s / b
    }
    val r = Math.atan(b/la)
    ans = r * 180 / Math.PI

    println(String.format("%.10f",ans))
}