import java.util.*;
public class Main{
    private static List<Integer>[]list=new List[]{
      Arrays.asList(1,3),Arrays.asList(0,2,4),Arrays.asList(1,5),
      Arrays.asList(0,4,6),Arrays.asList(1,3,5,7),Arrays.asList(2,4,8),
      Arrays.asList(3,7),Arrays.asList(4,6,8),Arrays.asList(5,7)
    };
    public static void main(String[]args){
        Scanner sc=new Scanner(System.in);
        String ss[]=sc.nextLine().split(" ");
        StringBuilder sb=new StringBuilder();
        for(String s:ss)sb.append(s);
        String start=sb.toString();
        String end="12345678x";
        Queue<String>q=new LinkedList<>();
        Set<String>set=new HashSet<>();
        q.add(start);
        set.add(start);
        int res=0;
        while(!q.isEmpty()){
             int sz=q.size();
             for(int i=0;i<sz;i++){
                  String cur=q.poll();
                  if(end.equals(cur)) {
                      System.out.println(res);
                      return ;
                  }
                  char c[]=cur.toCharArray();
                  int pos=0;
                  while(c[pos]!='x') pos++;
                  for(int next:list[pos]){
                      swap(c,pos,next);
                      String str=new String(c);
                      swap(c,pos,next);
                      if(!set.contains(str)){
                          set.add(str);
                          q.add(str);
                      }
                  }
             }
             res++;
        }
        System.out.println("-1");

    }
    private static void swap(char c[],int i,int j){
         char t=c[i];c[i]=c[j];c[j]=t;
    }
}