import java.util.*;

public class Main {
    public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int count = 0;
		for(int i = 1 ; i <= n ; i++){
			String str = String.valueOf(i);
			if( str.equals("8") ){
				count++; 
			}
		}
		System.out.println(count);
    }
}