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;
using std::map;
const int CMAX = 100005;
const char Cfd[] = "", Cfr[] = "";
long long res;
int Full(int len) { return (int)pow(2.0, len); }
int solve(string n) {
  if (n.length() == 1) return (n[0] == '0' ? 1 : 2);
  if (n[0] > '1') return Full(n.length());
  if (n[0] == '1') return (Full(n.length() - 1) + solve(n.substr(1)));
  return solve(n.substr(1));
}
int main() {
  string s;
  cin >> s;
  cout << solve(s) - 1;
  return 0;
}
