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 conBinary(int x) {
  string binary;
  while (x >= 1) {
    binary = (char)(x % 2 + 48) + binary;
    x = x / 2;
  }
  return atoi(binary.c_str());
}
int main() {
  int i;
  int x;
  int max;
  cin >> max;
  for (i = 1; i <= 513; i++) {
    x = conBinary(i);
    if (x > max) {
      x = i - 1;
      break;
    }
  }
  cout << x;
  return 0;
}
