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;
const int MOD = 1e9 + 7;
const long double PI = 4 * atan((long double)1);
long long power(long long a, long long n) {
  long long res = 1;
  while (n) {
    if (n % 2) res *= a;
    a *= a;
    n /= 2;
  }
  return res;
}
int main() {
  int n;
  cin >> n;
  vector<long long> v;
  v.push_back(1);
  long long int x = 10;
  while (1) {
    if (x > pow(10, 9)) break;
    int n = v.size();
    for (int j = 0; j < n; j++) {
      v.push_back(x + v[j]);
    }
    v.push_back(x);
    x = x * 10;
  }
  long long int cnt = 0;
  for (int i = 0; i < v.size(); i++) {
    if (v[i] <= n) cnt++;
  }
  cout << cnt;
  return 0;
}
