import math
a,b,x = map(int,input().split())
if x / a >= (a*b/2):
    print(math.degrees(math.atan((2*b/a)-2*x/(a**3))))
else:
    if a < b:
        print(math.degrees(math.atan(a*b*b/(2*x))))
    else:
        print(math.degrees(math.atan(2*x/(a*b*b))))
