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 mypow(int num, int n) {
  int r = 1;
  for (int i = 0; i < n; i++) {
    r *= num;
  }
  return r;
}
int highest(int num) {
  int r = 0;
  for (int i = 0; (mypow(10, i)) <= num; i++) {
    r = i;
  }
  return r;
}
int bin(int num) {
  int r = 0;
  int t = num;
  for (int i = highest(t); i >= 0; i--) {
    if (t >= mypow(10, i)) {
      r += mypow(10, i);
      t = t - mypow(10, i);
    }
  }
  return r;
}
int main() {
  int n;
  cin >> n;
  int b = bin(n);
  int r = 0;
  for (int i = highest(b); i >= 0; i--) {
    if ((b / (mypow(10, i))) % 10 == 1) {
      r += (1 << (i));
    }
  }
  if (b == 1) {
    cout << 1 << endl;
  } else {
    cout << r << endl;
  }
  return 0;
}
