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;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
ull pow2(ull n) { return 1 << n; }
ull Plus1(ull n) {
  int a = 1, k = 0;
  while (n % 10 == 1) {
    n /= 10;
    k++;
  }
  n++;
  for (int i = 1; i <= k; i++) n *= 10;
  return n;
}
int main() {
  int n;
  cin >> n;
  int a = 1;
  int ans = 0;
  while (int(log10(a)) < int(log10(n))) {
    ans += pow2(int(log10(a)));
    a *= 10;
  }
  while (a <= n) {
    a = Plus1(a);
    ans++;
  }
  cout << ans;
}
