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;
long long power(long long a, long long b) {
  long long val = 1;
  for (long long i = 1; i <= b; i++) {
    val *= 10;
  }
  return val;
}
int main() {
  long long n, i, j, val, k, x;
  cin >> n;
  for (i = 1; i <= 512; i++) {
    k = i;
    j = 0;
    val = 0;
    while (k > 0) {
      x = k % 2;
      val += (x * (power(10, j)));
      k /= 2;
      j++;
    }
    if (val > n) break;
  }
  cout << i - 1 << endl;
  return 0;
}
