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 n;
vector<int> a;
void get(int p, int id, int val) {
  if (p == id) {
    a.push_back(val);
    return;
  }
  if (p != 0) get(p + 1, id, val * 10);
  get(p + 1, id, val * 10 + 1);
}
int main() {
  cin.sync_with_stdio(0);
  cin.tie();
  cin >> n;
  for (int i = 1; i <= 9; i++) get(0, i, 0);
  sort(a.begin(), a.end());
  a.push_back(1000000000);
  a.push_back(1000000001);
  for (int i = 0; i < a.size(); i++) {
    if (n < a[i]) {
      cout << i << "\n";
      return 0;
    }
  }
}
