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 main() {
  int n, sum = 0;
  cin >> n;
  for (int a = 0; a <= 1; a++) {
    for (int b = 0; b <= 1; b++) {
      for (int c = 0; c <= 1; c++) {
        for (int d = 0; d <= 1; d++) {
          for (int e = 0; e <= 1; e++) {
            for (int f = 0; f <= 1; f++) {
              for (int g = 0; g <= 1; g++) {
                for (int h = 0; h <= 1; h++) {
                  for (int i = 0; i <= 1; i++) {
                    for (int j = 0; j <= 1; j++) {
                      long long num;
                      num = a * 1000000000 + b * 100000000 + c * 10000000 +
                            d * 1000000 + e * 100000 + f * 10000 + g * 1000 +
                            h * 100 + i * 10 + j;
                      if (num > n) {
                        goto A;
                      }
                      sum++;
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
A:
  cout << sum - 1 << endl;
  return 0;
}
