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;
vector<long long int> v;
void gen(int i, int d, long long int n) {
  if (i == 0) {
    gen(i + 1, d, 1);
  } else if (i == d - 1) {
    v.push_back(n * 10);
    v.push_back(n * 10 + 1);
  } else {
    gen(i + 1, d, n * 10);
    gen(i + 1, d, n * 10 + 1);
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  v.push_back(1);
  int i;
  for (i = 2; i <= 10; i++) {
    gen(0, i, 0);
  }
  int sz = v.size();
  long long int n, ans = 0;
  cin >> n;
  for (i = 0; i < sz; i++) {
    if (v[i] > n) break;
    ans++;
  }
  cout << ans;
  return 0;
}
