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;
long long ans = 0;
map<int, int> mrk;
void solve(long long x) {
  if (mrk[x]) return;
  mrk[x] = true;
  if (x <= n && x != 0) ans++;
  if (x > n) return;
  solve(10 * x + 1);
  solve(10 * x + 0);
}
int main() {
  scanf("%d", &n);
  solve(0);
  printf("%I64d\n", ans);
  return 0;
}
