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;
int32_t main() {
  ios::sync_with_stdio(false);
  long long n;
  cin >> n;
  deque<long long> q;
  q.push_back(1);
  long long x = 1, ans = 0;
  while (x <= n) {
    x = 1;
    long long y = 1;
    for (long long i = q.size() - 1; i >= 0; --i) {
      if (i != q.size() - 1) {
        x *= 10;
        x += q[i];
      }
    }
    if (x <= n) ++ans;
    bool c = false;
    for (long long i = 0; i < q.size(); ++i) {
      if (q[i] == 1) {
        q[i] = 0;
      } else {
        c = true;
        ++q[i];
        break;
      }
    }
    if (!c) q.push_back(1);
  }
  cout << ans;
}
