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;
inline bool checkBit(long long n, int i) { return n & (1ll << i); }
inline long long setBit(long long n, int i) {
  return n | (1ll << i);
  ;
}
inline long long resetBit(long long n, int i) { return n & (~(1ll << i)); }
const long long mod = 1e9 + 07;
const long long mxn = 1e6 + 10;
long long n;
vector<long long> vec;
void possible(long long m) {
  if (m > n) {
    return;
  }
  vec.push_back(m);
  possible(10 * m);
  possible(10 * m + 1);
}
int main(int argc, char const *argv[]) {
  long long i, j, k, a, b, c, d, m, t, h, u, v, x, y, z;
  cin >> n;
  possible(1);
  cout << (long long)vec.size() << "\n";
  return 0;
}
