#include <bits/stdc++.h>
using namespace std;

int main(){

  int n;
  cin >> n;
  int i=0,j = n,l=j*10;
  while(j>9) {
    i++;
    j/=10;
    l/=10;
  }
  l%=10;
  
  //cout << n << ' ' << i << ' ' << j << ' ' << l << endl;
  int count;
  if(j==9) count =4;
  else if(j>=6) count = 3;
  else if(j>=3) count = 2;
  else count = 1;
  
  for(int k=0; k<i; k++) count *=4;
  //cout << count << endl;

  if(i>=1) count -= 4;
  else count=0;
  //cout << count << endl;

  int lim = min(n,99);
  for(int k=10; k<=lim; ++k) {
    if((k/10)%3!=0 && k%3==0 ) count ++;
  }

  cout << count << endl;
}