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.
(function(n){

	var binary_number = 0,
		binary_digit_count = 0;

	while(n > 0){
		n_mod = n % 10;

		if(n_mod > 1){
			binary_number = (1 << binary_digit_count+1) - 1;
		} else if(n_mod == 1){
			binary_number |= 1 << binary_digit_count;
		}

		binary_digit_count++

		n = (n - n_mod) / 10;
	}

	print(binary_number);
})(+readline());