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> a;
void solve(int p, long long g) {
  a.push_back(g);
  if (p >= 10) return;
  solve(p + 1, g * 10 + 1);
  solve(p + 1, g * 10 + 0);
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  solve(0, 0);
  sort(a.begin(), a.end());
  a.erase(unique(a.begin(), a.end()), a.end());
  long long n;
  cin >> n;
  auto p = upper_bound(a.begin(), a.end(), n) - a.begin();
  cout << p - 1 << '\n';
  return 0;
}
