# 142 A

n = int(input())
odd = 0

for i in range(1, n+1):
    if i % 2 != 0:
        odd += 1

x = odd/n
print('%.10f' % x) n = int(input()) n int(input()) int input() input odd = 0 odd 0 for i in range(1, n+1):
    if i % 2 != 0:
        odd += 1 i range(1, n+1) range 1 n+1 n 1 if i % 2 != 0:
        odd += 1 i % 2 != 0 i % 2 i 2 0 odd += 1 odd 1 x = odd/n x odd/n odd n print('%.10f' % x) print '%.10f' % x '%.10f' x odd = 0 0 odd odd += 1 1 odd n = int(input()) int(input()) n x = odd/n odd/n x
# 142 A

n = int(input())
odd = 0

for i in range(1, n+1):
    if i % 2 != 0:
        odd += 1

x = odd/n
print('%.10f' % x)