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 arr[1 << 13];
int tot = 0;
void gen() {
  for (int i = 1; i <= (1 << 9); i++) {
    int tmp = 0;
    for (int j = 9; j >= 0; j--) {
      tmp = tmp * 10 + ((i >> j) & 1);
    }
    arr[tot++] = tmp;
  }
}
int main() {
  gen();
  int n;
  cin >> n;
  int l = 0, r = tot - 1, m, ret;
  while (l <= r) {
    m = (l + r) / 2;
    if (arr[m] <= n) {
      ret = m;
      l = m + 1;
    } else
      r = m - 1;
  }
  cout << ret + 1 << endl;
}
