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;
int n, cnt;
int po[999994], cr[14];
map<int, int> mert;
void calc(int L) {
  int x = 0;
  for (int i = 1; i <= L; i++) x = x * 10 + cr[i];
  if (x == 0)
    return;
  else if (!mert.count(x)) {
    mert[x] = 1;
    po[++cnt] = x;
  }
}
void dfs(int cur, int limit) {
  if (cur > limit)
    calc(limit);
  else
    for (int i = 0; i <= 1; i++) {
      cr[cur] = i;
      dfs(cur + 1, limit);
    }
}
int main() {
  cin >> n;
  for (int i = 1; i <= 10; i++) dfs(1, i);
  sort(po + 1, po + cnt + 1);
  int i = 0;
  for (i = 1; po[i] <= n; i++)
    ;
  cout << i - 1 << endl;
  return 0;
}
