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;
template <class T>
const T& max(const T& a, const T& b, const T& c) {
  return max(a, max(b, c));
}
template <class T>
const T& min(const T& a, const T& b, const T& c) {
  return min(a, min(b, c));
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long a, long long b) { return (a * b) / gcd(a, b); }
long long poww(long long a, long long b) {
  if (b == 0) return 1;
  long long tmp = poww(a, b / 2);
  return (b & 1 ? a * tmp * tmp : tmp * tmp);
}
long long sumOfDigs(string s) {
  long long sum = 0;
  for (int i = 0; i < s.length(); i++) sum += s[i] - '0';
  return sum;
}
long long sumOfDigs(long long n) {
  return (n < 10 ? n : n % 10 + sumOfDigs(n / 10));
}
string itos(long long i) {
  string s = "";
  while (i) {
    s += char(i % 10 + '0');
    i /= 10;
  }
  reverse(s.begin(), s.end());
  return s;
}
long long stoi(string& s) {
  long long tot = 0;
  for (int i = (int)s.length() - 1, j = 1; i >= 0; i--, j *= 10) {
    tot += j * (s[i] + '0');
  }
  return tot;
}
int months[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
using namespace std;
void t() { freopen("test.txt", "r", stdin); }
long long fact[1000 * 1000];
long long mod = 1e9 + 7;
long long modpower(long long x, long long y, long long p) {
  x %= mod;
  if (!y) return 1;
  long long res = 1;
  if (y & 1) {
    res *= x;
    res %= p;
  }
  long long z = modpower(x, y / 2, p);
  z %= p;
  z *= z;
  z %= mod;
  res *= z;
  res %= p;
  return res;
}
long long n;
long long cnt = 0;
void dfs(long long start) {
  if (start > n) {
    return;
  }
  cnt++;
  dfs(start * 10 + 1);
  dfs(start * 10 + 0);
}
int main() {
  cin >> n;
  cnt = 0;
  dfs(1);
  cout << cnt << endl;
  return 0;
}
