#-----------------------------------------------------------------------
# harmonic.py
#-----------------------------------------------------------------------

import stdio
import sys

# Accept integer n as a command-line argument. Write to standard
# output the value of the nth harmonic number.

n = int(sys.argv[1])

total = 0.0
for i in range(1, n+1):
    # Add the ith term to the sum
    total += 1.0 / i

stdio.writeln(total)

#-----------------------------------------------------------------------

# python harmonic.py 2
# 1.5

# python harmonic.py 10
# 2.9289682539682538

# python harmonic.py 10000
# 9.787606036044348