import std.algorithm;
import std.bigint;
import std.bitmanip;
import std.concurrency;
import std.container;
import std.conv;
import std.functional;
import std.format;
import std.math;
import std.meta;
import std.numeric;
import std.random;
import std.range;
import std.stdio;
import std.string;
import std.traits;
import std.typecons;


auto solve(long a, long b, long x) {
    return a * a * b / 2.0 <= x ?
        atan(2.0 * (a * a * b - x) / a ^^ 3) * 180.0 / PI :
        atan((a * b * b) / 2.0 / x) * 180.0 / PI;
}


void main() {
    auto input = stdin.byLine.map!split.joiner;

    long a;
    a = input.front.to!long;
    input.popFront;

    long b;
    b = input.front.to!long;
    input.popFront;

    long x;
    x = input.front.to!long;
    input.popFront;

    static if (is(ReturnType!solve == void))
        solve(a, b, x);
    else {
        auto ans = solve(a, b, x);

        static if (isFloatingPoint!(ReturnType!solve))
            writeln(format("%.9f", ans));
        else static if (is(ReturnType!solve == bool))
            writeln(ans ? YES : NO);
        else
            writeln(ans);
    }
}
