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>
#pragma GCC optimize("O3")
#pragma GCC target("sse4")
using namespace std;
const int maxn = 2e5 + 5;
const int mod = 1000000007;
const long long INF = 1e18;
const int MX = 2000000001;
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0);
  long long t, q, n, ar, b, k, l, m, r, x = 0, y = 0, ans = 0, temp = 0,
                                        res = 0;
  string second, answ = "";
  cin >> second;
  n = second.length();
  for (long long i = 0; i < (n); i++) {
    if (second[i] > '1') {
      for (long long j = i; j < (n); j++) answ.push_back('1');
      break;
    } else
      answ.push_back(second[i]);
  }
  long long pow[20];
  pow[0] = 1;
  for (long long i = 1; i < (20); i++) pow[i] = pow[i - 1] * 2;
  for (long long i = 0; i < (n); i++) ans += pow[n - i - 1] * (answ[i] - '0');
  cout << ans;
}
