n = int(input())
d,m = divmod(n,4)
b1 = 10000 ** d
b2 = 10 ** m
b = b1 * b2
cnt = str(b // 7).zfill(n)
cnt = b // 7
if cnt > 0 :
    cnt = "0." + str(b // 7).zfill(n)
print(cnt)