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 fun(long long a) {
  long long j = 0;
  while (a--) {
    j *= 10;
    j++;
  }
  return j;
}
int main() {
  long long n, i, j = 1, k, a, b = 0;
  cin >> n;
  while (1) {
    k = n;
    long long cnt = 0;
    vector<long long> v;
    while (n > 0) {
      v.push_back(n % 10);
      n /= 10;
      cnt++;
    }
    a = fun(cnt);
    if (k >= a) {
      cout << b + pow(2, cnt) - 1;
      return 0;
    } else
      b += pow(2, cnt - 1);
    n = 0;
    for (i = v.size() - 2; i >= 0; i--) {
      n *= 10;
      n += v[i];
    }
  }
}
