import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")


n = int(input())
ans = ((n+1)//2) / n
print(ans) import sys sys input = lambda : sys.stdin.readline().rstrip() input lambda : sys.stdin.readline().rstrip() sys.stdin.readline().rstrip() sys.stdin.readline().rstrip sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline rstrip sys.setrecursionlimit(max(1000, 10**9)) sys.setrecursionlimit sys setrecursionlimit max(1000, 10**9) max 1000 10**9 10 9 write = lambda x: sys.stdout.write(x+"\n") write lambda x: sys.stdout.write(x+"\n") sys.stdout.write(x+"\n") sys.stdout.write sys.stdout sys stdout write x+"\n" x "\n" x n = int(input()) n int(input()) int input() input ans = ((n+1)//2) / n ans ((n+1)//2) / n (n+1)//2 n+1 n 1 2 n print(ans) print ans n = int(input()) int(input()) n ans = ((n+1)//2) / n ((n+1)//2) / n ans input = lambda : sys.stdin.readline().rstrip() lambda : sys.stdin.readline().rstrip() input write = lambda x: sys.stdout.write(x+"\n") lambda x: sys.stdout.write(x+"\n") write
import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")


n = int(input())
ans = ((n+1)//2) / n
print(ans)