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> num;
void sol(long long n) {
  if (n >= 1000000001) return;
  num.push_back(n);
  sol(n * 10);
  sol(n * 10 + 1);
}
int main() {
  long long n;
  cin >> n;
  sol(1);
  int ans = 0;
  sort(num.begin(), num.end());
  for (int i = 0; i < num.size(); i++) {
    if (num[i] <= n) ans++;
  }
  cout << ans;
  return 0;
}
