k=0
a=int(input())
for i in range(1,a+1,2):
       k=k+1
print(k/a) k=0 k 0 a=int(input()) a int(input()) int input() input for i in range(1,a+1,2):
       k=k+1 i range(1,a+1,2) range 1 a+1 a 1 2 k=k+1 k k+1 k 1 print(k/a) print k/a k a a=int(input()) int(input()) a k=k+1 k+1 k k=0 0 k
k=0
a=int(input())
for i in range(1,a+1,2):
       k=k+1
print(k/a)