n = int(input())
a = 0

for i in range(n,1,-1):
    if i % 2 == 1:
        a = a + 1

a = a + 1
print('{:.08f}'.format(a / n)) n = int(input()) n int(input()) int input() input a = 0 a 0 for i in range(n,1,-1):
    if i % 2 == 1:
        a = a + 1 i range(n,1,-1) range n 1 -1 if i % 2 == 1:
        a = a + 1 i % 2 == 1 i % 2 i 2 1 a = a + 1 a a + 1 a 1 a = a + 1 a a + 1 a 1 print('{:.08f}'.format(a / n)) print '{:.08f}'.format(a / n) '{:.08f}'.format '{:.08f}' format a / n a n a = a + 1 a + 1 a a = a + 1 a + 1 a n = int(input()) int(input()) n a = 0 0 a
n = int(input())
a = 0

for i in range(n,1,-1):
    if i % 2 == 1:
        a = a + 1

a = a + 1
print('{:.08f}'.format(a / n))