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;
queue<int> q;
int k, n, w, m;
int main() {
  cin >> n;
  q.push(1);
  while (!q.empty()) {
    w = q.front();
    q.pop();
    if (w * 10 <= n) q.push(w * 10);
    if (w * 10 + 1 <= n) q.push(w * 10 + 1);
    k++;
  }
  cout << k;
}
