R,O=range,print
T=10**7
N=int(input())
if N<1:O(0.4),exit()
U=0
for x in R(T+1):
	y=(x**3+(N*T)**3)*10
	l,r=0,y
	while l+1<r:
		m=(l+r)//2
		if m*m>y:r=m
		else:l=m
	U+=l
	if x<1:L=l
L=str(U-l)
L="0"*(19-len(L))+L
L=L[:-18]+"."+L[-18:],U[:-18]+"."+U[-18:]
O(L[:-18]+"."+L[-18:-12])