## Algorithm

time limit per test
1 second
memory limit per test
64 megabytes
input
standard input
output
standard output

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
Copy
`10`
output
Copy
`2`
Note

For n = 10 the answer includes numbers 1 and 10.

## Code Examples

### #1 Code Example with C++ Programming

```Code - C++ Programming```

``````#include <bits/stdc++.h>

using namespace std;

vector<long long> all;
void rec(long long sum, int idx) {
if(idx == 10) {
all.push_back(sum);
return;
}

rec(sum, idx + 1);
rec(sum * 10, idx + 1);
rec(sum * 10 + 1, idx + 1);
}

int main() {
rec(1, 0);
sort(all.begin(), all.end());
all.resize(unique(all.begin(), all.end()) - all.begin());

int n, res = 0;
scanf("%d", &n);
for(int i = 0; i < (int)all.size(); ++i) {
if(all[i] > n)
break;
++res;
}
printf("%d\n", res);

return 0;
}``````
Copy The Code &

Input

cmd
10

Output

cmd
2