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 dx[] = {1, 1, 0, -1, -1, -1, 0, 1};
int dy[] = {0, 1, 1, 1, 0, -1, -1, -1};
template <typename T>
void printV(vector<T> v) {
  for (int i = 0; i < v.size(); i++) {
    cout << v[i] << " ";
  }
  cout << endl;
}
int total = 0;
void solve(int n, int cur) {
  if (cur > n) {
    return;
  }
  if (cur <= n) {
    total++;
  }
  solve(n, cur * 10);
  solve(n, cur * 10 + 1);
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  int i, j, k;
  int n;
  cin >> n;
  solve(n, 1);
  cout << total << endl;
  return 0;
}
