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;
const double eps = 1e-11;
const int inf = (int)2e9;
const int mod = (int)1e9 + 7;
const int N = 123456;
int n;
int ans;
int a[10];
void Back(int k, int l) {
  if (k == l) {
    long long cur = 0;
    for (int i = 0; i < l; i++) cur = cur * 10 + a[i];
    if (cur <= n) ans++;
  } else {
    for (int i = 0; i < 2; i++) {
      a[k] = i;
      Back(k + 1, l);
    }
  }
}
int main() {
  cin >> n;
  Back(0, 10);
  cout << ans - 1 << endl;
  return 0;
}
