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>
std::vector<int> dec2Bin(long n) {
  std::vector<int> output;
  while (n > 0) {
    output.push_back(n % 2);
    n /= 2;
  }
  return output;
}
long readDec(std::vector<int> input) {
  long output = 0;
  for (int k = input.size() - 1; k >= 0; k--) {
    output = 10 * output + input[k];
  }
  return output;
}
int main() {
  const int M = 1024;
  long n;
  scanf("%ld\n", &n);
  int output = 0;
  while (readDec(dec2Bin(++output)) <= n)
    ;
  printf("%d\n", --output);
  return 0;
}
