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.
#include <bits/stdc++.h>
using namespace std;
int main() {
  string aux;
  cin >> aux;
  int flag_Invalid_Input = 0;
  int memo[10] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512};
  int counter = 0;
  int len = aux.size();
  int i, j;
  for (i = 0; i < len; i++) {
    if (aux[i] > '1') {
      for (j = 0; j < len - i; j++) {
        counter += memo[j];
      }
      break;
    }
    if (aux[i] == '1') {
      counter += memo[len - i - 1];
    }
  }
  cout << counter;
}
