def Riemann_zeta_function(N):
    result = 0.0
    num    = 1
    flag   = True
    
    while flag:
        result += 1/pow(num,N)
        
        if abs(result- int(result)) <= 10**(-10):
            flag = False
    return result
    
N = int(input())
print(Riemann_zeta_function(N))