import math

a,b,x = (int(num) for num in input().split())
suf2 = a*b
vol = a*a*b
if (vol/2)>=x:
    l = x*2 / suf2
    x = b/l
    ans = math.degrees(math.atan(x))
else:
    l = (vol-x)*2 / (a*a)
    x = l/a
    ans = math.degrees(math.atan(x))
    
print(round(ans,6))
