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 long long inf = 9e18;
const double pi = acos(-1.0);
const long long M = 1e9 + 7;
const long long N = 1e5 + 5;
long long power(long long n, long long m) {
  long long res(1);
  while (m) {
    if (m & 1) res *= n;
    n *= n;
    m /= 2;
  }
  return res;
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  vector<long long> v;
  v.push_back(0);
  v.push_back(1);
  long long l = 9, j = 1;
  while (l--) {
    long long n = power(10, j);
    long long k = (long long)v.size();
    for (long long i = 0; i < k; i++) {
      v.push_back(n + v[i]);
    }
    j++;
  }
  long long n;
  cin >> n;
  cout << upper_bound(v.begin(), v.end(), n) - v.begin() - 1;
}
