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>
long long mod = 1e9 + 7;
const int MAX = 1e5 + 5;
using namespace std;
long long get_binary(int n) {
  long long binary = 0;
  int remainder, i = 1, step = 1;
  while (n != 0) {
    remainder = n % 2;
    n /= 2;
    binary += remainder * i;
    i *= 10;
  }
  return binary;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  long long cnt = 0;
  for (int i = 1; i <= (int)pow(2, 10) - 1; i++) {
    int num = i;
    long long bin = get_binary(num);
    if (bin <= n) cnt++;
  }
  cout << cnt;
  return 0;
}
