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() {
  vector<long long> a;
  a.push_back(0);
  a.push_back(1);
  map<long long, long long> m;
  int k, l = 0;
  m[0] = 1;
  m[1] = 1;
  while (1) {
    k = l;
    l = a.size();
    for (int i = k; i < l; i++) {
      long long z = a[i] * 10 + 0;
      long long y = a[i] * 10 + 1;
      if (m[z] == 0) {
        a.push_back(z);
        m[z]++;
      }
      if (m[y] == 0) {
        a.push_back(y);
        m[y]++;
      }
    }
    if (a[a.size() - 1] > 1e9) break;
  }
  long long n;
  cin >> n;
  vector<long long>::iterator it;
  it = upper_bound(a.begin(), a.end(), n);
  cout << it - a.begin() - 1 << endl;
}
