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

int N;
int n=0;

void keisan(long int x,int a,int b,int c){
  if(x>N)
    return;
  if(a&&b&&c)
    n++;
  
  keisan(x*10+3,1,b,c);
  keisan(x*10+5,a,1,c);
  keisan(x*10+7,a,b,1);
}

int main(){
  cin>>N;
  keisan(0,0,0,0);
  cout<<n<<endl;
}
