def ABC_142_A():
    N = int(input())
    guusuu=0
    for i in range(N+1):
        if i%2 == 0 and i !=0:
            guusuu+=1

    print(1-(guusuu/N))




if __name__ == '__main__':

    ABC_142_A() def ABC_142_A():
    N = int(input())
    guusuu=0
    for i in range(N+1):
        if i%2 == 0 and i !=0:
            guusuu+=1

    print(1-(guusuu/N)) ABC_142_A N = int(input()) N int(input()) int input() input guusuu=0 guusuu 0 for i in range(N+1):
        if i%2 == 0 and i !=0:
            guusuu+=1

     i range(N+1) range N+1 N 1 if i%2 == 0 and i !=0:
            guusuu+=1

     i%2 == 0 and i !=0 i%2 == 0 i%2 i 2 0 i !=0 i 0 guusuu+=1 guusuu 1 print(1-(guusuu/N)) print 1-(guusuu/N) 1 guusuu/N guusuu N if __name__ == '__main__':

    ABC_142_A() __name__ == '__main__' __name__ '__main__' ABC_142_A() ABC_142_A def ABC_142_A():
    N = int(input())
    guusuu=0
    for i in range(N+1):
        if i%2 == 0 and i !=0:
            guusuu+=1

    print(1-(guusuu/N)) def ABC_142_A():
    N = int(input())
    guusuu=0
    for i in range(N+1):
        if i%2 == 0 and i !=0:
            guusuu+=1

    print(1-(guusuu/N)) ABC_142_A
def ABC_142_A():
    N = int(input())
    guusuu=0
    for i in range(N+1):
        if i%2 == 0 and i !=0:
            guusuu+=1

    print(1-(guusuu/N))




if __name__ == '__main__':

    ABC_142_A()