x=int(input())
ans=0
if 3<=x<=100:
    for k in range(2,100000):
        ans+=10**18/(k**(x-1)*(k-1))
elif x==2:
    ans=10**18
else:
    for k in range(2,100):
        ans+=10**18/(k**(x-1)*(k-1))

print(int(ans)//10**12)