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>
int main() {
  int i, j, res = 0;
  char c, s[100];
  gets(s);
  for (i = 0; i < strlen(s); i++) {
    c = s[i];
    if (('2' <= c) && (c <= '9')) {
      for (j = i + 1; j < strlen(s); j++) s[j] = '1';
      break;
    }
  }
  for (i = 0; i < strlen(s); i++) {
    c = s[i];
    if (c == '0') res *= 2;
    if (('0' < c) && (c <= '9')) res = 2 * res + 1;
  }
  printf("%d\n", res);
  return 0;
}
