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;
void judge(char x[]) {
  int i = 0;
  while (x[i] && x[i] < '2') {
    ++i;
  }
  while (x[i]) {
    x[i++] = '1';
  }
}
int change(char x[]) {
  judge(x);
  int ans = 0, base = 1;
  for (int i = 0; x[i]; ++i) {
    ans = ans * 2 + x[i] - '0';
  }
  return ans;
}
int main() {
  char x[15];
  scanf("%s", x);
  printf("%d\n", change(x));
  return 0;
}
