import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
import std.container;

enum MAX = 1_000_100;
ulong MOD = 1_000_000_007;
ulong INF = 1_000_000_000_000;
alias sread = () => readln.chomp();
alias Pass = Tuple!(long, "x", long, "y");

void main()
{
    real a, b, x;
    scan(a, b, x);
    real inv;
    if (2 * x / a <= a * b)
        inv = (a * (b ^^ 2) / (2 * x));
    else
        inv = (2 * x - 2 * (a ^^ 2) * b) / (a ^^ 3);

    auto sita = atan(inv);
    writefln("%3.12s", abs(sita * 180 / PI));
}

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}
