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;
inline bool verify(int n) {
  while (n) {
    int c = n % 10;
    n /= 10;
    if (c == 1 || c == 0) continue;
    return false;
  }
  return true;
}
int main() {
  ios_base::sync_with_stdio(false);
  int n;
  cin >> n;
  int nrd = (int)log10(n) + 1;
  int i = 0, ans = 0;
  while (i < nrd - 1) {
    ans += (1 << i);
    ++i;
  }
  int nr = 0;
  while ((int)log10(nr) + 1 < nrd) {
    nr = nr * 10 + 1;
  }
  nr = min(n, nr);
  for (int i = int(pow(10, nrd - 1)); i <= nr; ++i) ans += verify(i);
  cout << ans;
}
