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;
long long n, arr[1026];
long long to_dec(string s) {
  long long res = 0, y = s.size();
  for (int i = 0; i < y; i++) res *= 10, res += (s[i] - 48);
  return res;
}
void solve() {
  long long x;
  for (int i = 1; i <= 1024; i++) {
    x = i;
    string k;
    while (x) k.push_back((x % 2) + 48), x /= 2;
    reverse(k.begin(), k.end());
    arr[i] = to_dec(k);
  }
}
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  ;
  solve();
  cin >> n;
  cout << upper_bound(arr, arr + 1024, n) - arr - 1 << endl;
  return 0;
}
