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 powe(int a, int b) {
  int r = 1, i;
  for (i = 1; i <= b; i++) r = r * a;
  return r;
}
int main() {
  int N, i, j, k;
  cin >> N;
  int copy = N, r = 0;
  while (copy > 0) {
    copy = copy / 10;
    r++;
  }
  int a[r + 1];
  copy = N;
  int c = r;
  if (r == 1) {
    cout << 1;
    return 0;
  }
  i = 1;
  while (c > 0) {
    a[i++] = copy / powe(10, c - 1);
    copy = copy % powe(10, c - 1);
    c--;
  }
  int count = r + 1;
  int result;
  result = powe(2, r) - 1;
  for (i = r; i >= 1; i--) {
    if (a[i] > 1) count = i;
  }
  for (int j = 1; j < count; j++) {
    if (a[j] == 0) {
      result = result - powe(2, r - j);
    } else
      continue;
  }
  cout << result;
}
