One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.
original,i = input(),0
number = list(map(int, original))
bigger = 15
for j in range(len(number)):
	if number[j] > 1 and j < bigger: bigger = j;
	if int(original[j]) > 1: number[j] =1;
	elif original[j] == "0" and bigger < 15: number[j] = 1;
print(int("".join(str(x) for x in number),base=2))