import os
import numpy as np

class getStdin(object):
    @classmethod
    def get_int(cls):
        return int(input())

    @classmethod
    def get_ss_int(cls):
        return list(map(float, input().split()))

    @classmethod
    def get_na_int(cls):
        return np.array(sorted(list(map(int, input().split()))))

    @classmethod
    def get_na_intr(cls):
        return np.array(sorted(list(map(int, input().split())))[::-1])


class funcCls(object):
    @classmethod
    def done(cls, a, b, x):
        import math
        mm = x / a
        if mm <= (a * b / 2):
            th = math.degrees(math.atan(b ** 2 / (2 * mm)))
        else:
            th = math.degrees(math.atan((-2*mm + 2*a*b) / a ** 2))

        return th


if __name__ == '__main__':
    a, b, x = getStdin.get_ss_int()
    y = funcCls.done(a, b, x)

    print(y)
    os.sys.exit(0)