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;
int dr[] = {0, 0, 1, -1, -1, -1, 1, 1};
int dc[] = {1, -1, 0, 0, -1, 1, -1, 1};
int const MAX = 1e6 + 7;
int const MOD = 1e9 + 7;
set<long long> ans;
void rec(string s) {
  if (s.length() == 11) return;
  if (s != "") ans.insert(stoll(s));
  rec(s + '0');
  rec(s + '1');
}
int main() {
  rec("");
  long long n, out = 0;
  scanf("%lld", &n);
  for (set<long long>::iterator it = ans.begin(); it != ans.end(); it++)
    if (*it <= n && *it > 0) out++;
  cout << out << "\n";
}
