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 main() {
  int n;
  scanf("%d", &n);
  vector<int> nm;
  for (int i = 1; i <= 1000; ++i) {
    int k = i;
    string s = "";
    while (k) {
      s += ((k & 1) + '0');
      k /= 2;
    }
    reverse(s.begin(), s.end());
    stringstream ss;
    int ad;
    ss << s;
    ss >> ad;
    nm.push_back(ad);
  }
  int an = 0;
  for (auto i : nm) {
    if (i <= n) ++an;
  }
  printf("%d\n", an);
}
