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;
const int mod = 1e9 + 7, mxn = 2e5 + 5;
set<long long> st;
long long n;
void dfs(string s) {
  long long x = stoll(s);
  if (x > n) return;
  st.insert(x);
  dfs(s + "1");
  dfs(s + "0");
  return;
}
long long mainx() {
  cin >> n;
  dfs("1");
  cout << (long long)st.size() << "\n";
  return 0;
}
bool cmp(pair<long long, long long> &a, pair<long long, long long> &b) {
  if (a.first < b.first) return true;
  if (a.first == b.first) return a.second < b.second;
  return false;
}
inline void INCLUDE() {}
int32_t main() {
  INCLUDE();
  ios::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  long long tt = 1;
  for (long long t = 1; t <= tt; t++) {
    mainx();
  }
  return 0;
}
