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 to_dec(int x) {
  int pot = 1;
  int acc = 0;
  while (x) {
    if (x & 1) acc += pot;
    pot *= 10;
    x >>= 1;
  }
  return acc;
}
int solve(int n) {
  int i = 1;
  while (to_dec(i) <= n) ++i;
  return i - 1;
}
int main() {
  int n;
  scanf("%d", &n);
  printf("%d\n", solve(n));
}
