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 long long NN = 1e10 + 7;
const int N = 1e5 + 7;
const int M = 11;
const long long mod = 1e9 + 7;
const long long inf = 1e18 + 7;
const double long rf = 1e-14;
void solve1() {
  int n, res = 0;
  cin >> n;
  vector<int> v[550];
  vector<int> s;
  for (int i = 1; i <= 512; i++) {
    int t = i, k = 0;
    while (t > 0) v[i].push_back(t % 2), t /= 2;
    reverse(v[i].begin(), v[i].end());
    for (auto j : v[i]) {
      k *= 10;
      k += j;
    }
    s.push_back(k);
  }
  for (auto i : s)
    if (n >= i) res++;
  cout << res;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  srand(time(0));
  int cghf = 1;
  while (cghf--) {
    solve1();
  }
}
