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 mp[1000];
int ith_decimal(int x) {
  int n = 0, i = 1;
  while (x != 0) {
    int rem = x % 2;
    x /= 2;
    n += rem * i;
    i *= 10;
  }
  return n;
}
void precal() {
  for (int i = 1; i <= 512; i++) {
    int x = ith_decimal(i);
    mp[i] = x;
  }
}
int main() {
  precal();
  int n;
  cin >> n;
  for (int i = 1; i <= 512; i++) {
    if (mp[i] == n) {
      cout << i << "\n";
      break;
    }
    if (mp[i] > n) {
      cout << i - 1 << "\n";
      break;
    }
  }
}
