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 to(int i) {
  long long s = 0, t = 1;
  while (i) {
    s += (i & 1) * t;
    t *= 10;
    i = i >> 1;
  }
  return s;
}
int main() {
  long long n, s = 0, i = 1;
  cin >> n;
  for (i = 1; i < 1000; i++)
    if (to(i) > n) break;
  cout << i - 1;
}
