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(void) {
  int n, ret = 0, i, j;
  scanf("%d", &n);
  if (n == 1000000000) ++ret, --n;
  for (i = 1; i < 1000000000 && i <= n; i *= 10) {
    int j = i / 10, t = i, c = 0;
    while (j > 0) {
      j /= 10;
      c++;
    }
    j = i / 10;
    while (j > 0) {
      if (t + j <= n) {
        ret += 1 << c - 1;
        t += j;
      }
      j /= 10;
      --c;
    }
    ++ret;
  }
  printf("%d\n", ret);
  return 0;
}
