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>
const double e = 1e-7;
const int N = 111;
const long long mod = 1000000007;
using namespace std;
vector<long long> numbers;
void BACKTRACK(long long num, int i) {
  if (i == 10) return;
  numbers.push_back(num);
  BACKTRACK(num * 10, i + 1);
  BACKTRACK(num * 10 + 1, i + 1);
}
int main() {
  long long n;
  cin >> n;
  BACKTRACK(1, 0);
  sort(numbers.begin(), numbers.end());
  int k = 0;
  while (k < numbers.size() && numbers[k] <= n) ++k;
  cout << k << endl;
}
