#include<iostream>
using namespace std;
int n;

void dfs(int x,int a,int b,int c){
  int ans=0;
  if(x>n){
    return;
  }
  if(a&&b&&c)ans++;
    dfs(x*10+3,1,b,c);
    dfs(x*10+5,a,1,c);
    dfs(x*10+7,a,b,1);
}

int main(){
  cin>>n;
  dfs(0,0,0);
  cout<<ans<<endl;
}
