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;
const int N = 100110;
long long ipow(int base, int exp) {
  long long result = 1;
  while (exp) {
    if (exp & 1) result *= base;
    exp >>= 1;
    base *= base;
  }
  return result;
}
string NearestBinary(string s) {
  int i = 0;
  while (s[i] <= '1') i++;
  while (s[i]) s[i++] = '1';
  return s;
}
long long ToDecimal(string s) {
  int i = 0;
  long long ans = 0;
  while (!s.empty()) {
    ans += (s.back() - '0') * ipow(2, i);
    s.pop_back();
    i++;
  }
  return ans;
}
int main() {
  string n;
  cin >> n;
  n = NearestBinary(n);
  cout << ToDecimal(n);
  return 0;
}
