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>
int const up = 1e6 + 10;
int const up1 = 5 * 1e5 + 10;
int const eps = 1e-9;
int const MX = 5 * 1e5 + 10;
int const mod = 1e9 + 7;
using namespace std;
int main() {
  vector<long long int> v;
  long long int t = 1LL;
  for (int i = 1; i <= 11; i++) {
    v.push_back(t);
    int clen = v.size();
    for (int j = 0; j < clen - 1; j++) {
      v.push_back(t + v[j]);
    }
    t *= 10;
  }
  long long int n;
  cin >> n;
  int idx = upper_bound(v.begin(), v.end(), n) - v.begin();
  cout << idx;
  return 0;
}
