import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int r = sc.nextInt();
int f = f(r);
System.out.println(f);
}
public static int f(int n) {
if (n == 6174) {
return 0;
}
return f(res(n))+1;
}
public static int res(int n){
int nums[] = new int[4];
int cnt = 0;
while (n != 0){
int x = n%10;
nums[cnt++] = x;
n /= 10;
}
Arrays.sort(nums);
return ((nums[3]*1000+nums[2]*100+nums[1]*10+nums[0])-(nums[0]*1000+nums[1]*100+nums[2]*10+nums[3]));
}
}