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;
vector<int> v;
int dp[10][2];
int solve(int pos, int f) {
  if (pos == v.size()) return 1;
  if (dp[pos][f] != -1) return dp[pos][f];
  int res = 0;
  int bound = (f) ? v[pos] : 9;
  for (int d = 0; d <= min(1, bound); ++d) {
    int new_f;
    if (!f)
      new_f = 0;
    else {
      if (d < bound)
        new_f = 0;
      else
        new_f = 1;
    }
    res += solve(pos + 1, new_f);
  }
  dp[pos][f] = res;
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  while (n > 0) {
    v.push_back(n % 10);
    n /= 10;
  }
  reverse(v.begin(), v.end());
  memset(dp, -1, sizeof(dp));
  cout << solve(0, 1) - 1 << '\n';
  return 0;
}
