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 MXN = 1e6 + 1;
const int MAXN = 1e2 + 1;
const long long INF = 1e16 + 1;
const int MOD = 1e9 + 7;
const double EPS = 1e-9;
long long n;
long long res;
long long g[MXN];
bool q;
vector<int> v;
void rec(int x, int N) {
  if (x == N + 1) {
    q = 0;
    res = 0;
    for (int i = 1; i <= N; i++) {
      if (g[i] != 0) {
        q = 1;
      }
      if (q) {
        res *= 10;
        res += g[i];
      }
    }
    v.push_back(res);
  } else {
    g[x] = 1;
    rec(x + 1, N);
    g[x] = 0;
    rec(x + 1, N);
  }
}
int main() {
  cin >> n;
  long long a = n, cnt = 0;
  while (a != 0) {
    a /= 10;
    cnt++;
  }
  rec(1, cnt);
  sort(v.begin(), v.end());
  for (int i = 0; i < v.size(); i++) {
    if (v[i] > n) {
      cout << i - 1;
      return 0;
    }
  }
  cout << v.size() - 1;
  return 0;
}
