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() {
  long long n, cnt = 0;
  scanf("%lld", &n);
  for (int mask = 1; mask < (1 << 10); ++mask) {
    string str = "";
    int num;
    for (int i = 9; i >= 0; --i) {
      if (((mask >> i) & 1)) {
        str += "1";
      } else {
        str += "0";
      }
    }
    num = stoi(str);
    if (num <= n) {
      ++cnt;
    }
  }
  printf("%lld\n", cnt);
  return 0;
}
