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;
vector<long long> digits;
bool decToBinary(long long x, long long n) {
  long long binaryNum[32];
  long long i = 0, num = 0, val;
  while (x > 0) {
    binaryNum[i] = x % 2;
    x = x / 2;
    i++;
  }
  val = 1;
  for (long long j = 0; j <= i - 1; ++j) {
    num = num + binaryNum[j] * val;
    val *= 10;
  }
  if (num <= n)
    return true;
  else
    return false;
}
int main(void) {
  ios_base::sync_with_stdio(false), cin.tie(NULL);
  long long n, ans = 0, i;
  cin >> n;
  for (i = 1; i < 1025; ++i) {
    if (decToBinary(i, n)) {
      ans++;
    }
  }
  cout << ans << endl;
  return 0;
}
