import sys
import math
import bisect


def main():
    n = int(input())
    ans = ((n+1)//2) / n
    print('%.10f' % ans)



if __name__ == "__main__":
    main() import sys sys import math math import bisect bisect def main():
    n = int(input())
    ans = ((n+1)//2) / n
    print('%.10f' % ans) main n = int(input()) n int(input()) int input() input ans = ((n+1)//2) / n ans ((n+1)//2) / n (n+1)//2 n+1 n 1 2 n print('%.10f' % ans) print '%.10f' % ans '%.10f' ans if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def main():
    n = int(input())
    ans = ((n+1)//2) / n
    print('%.10f' % ans) def main():
    n = int(input())
    ans = ((n+1)//2) / n
    print('%.10f' % ans) main
import sys
import math
import bisect


def main():
    n = int(input())
    ans = ((n+1)//2) / n
    print('%.10f' % ans)



if __name__ == "__main__":
    main()
