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 q[15];
int main() {
  int n;
  scanf("%d", &n);
  int cnt = 0;
  while (1) {
    q[1] += 1;
    for (int i = 1; i <= 10; i++) {
      if (q[i] == 2) {
        q[i] = 0;
        q[i + 1] += 1;
      }
    }
    int sum = 0;
    for (int i = 1; i <= 10; i++) sum += q[i] * pow(10, i - 1);
    if (sum > n)
      break;
    else
      cnt++;
  }
  printf("%d\n", cnt);
  return 0;
}
