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;
char s[15], d[15];
const int dva[15] = {1,   2,   4,    8,    16,   32,   64,   128,
                     256, 512, 1024, 2048, 4096, 8192, 16384};
int main() {
  long long nn;
  scanf("%lld", &nn);
  sprintf(s, "%lld", nn);
  int n = strlen(s);
  int i = 0;
  while (s[i] == '1' || s[i] == '0') {
    d[i] = s[i];
    i++;
  }
  while (i < n) {
    d[i] = '1';
    i++;
  }
  int r = 0;
  for (int i = 0; i < n; i++) r += (d[i] - '0') * dva[n - i - 1];
  printf("%d\n", r);
  return 0;
}
