
n=int(input())
if n%2==0:
    print('0.5000000000')
elif n==1:
    print('1.000000000')
else:
    print((n//2 + 1)/n) n=int(input()) n int(input()) int input() input if n%2==0:
    print('0.5000000000')
elif n==1:
    print('1.000000000')
else:
    print((n//2 + 1)/n) n%2==0 n%2 n 2 0 print('0.5000000000') print '0.5000000000' elif n==1:
    print('1.000000000') n==1 n 1 print('1.000000000') print '1.000000000' print((n//2 + 1)/n) print (n//2 + 1)/n n//2 + 1 n//2 n 2 1 n n=int(input()) int(input()) n

n=int(input())
if n%2==0:
    print('0.5000000000')
elif n==1:
    print('1.000000000')
else:
    print((n//2 + 1)/n)