import math
a,b,x = map(int,input().split())
h = x/(a**2)
if b//2 >= h:

    d = 2*h*a/b

    sin = math.degrees(math.acos(d/((d**2+b**2)**0.5)))
    print(sin)
else:
    d = 2*(b-h)*a/a
    sin = math.degrees(math.acos(d/((d**2+a**2)**0.5)))
    print(90-sin)
