import java.io.*;
import java.util.*;

public class Main {



    static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));


    private static int bfs(String str,String end)
    {
        Queue<String> q = new LinkedList<>();
        Map<String,Integer> map = new HashMap<>();
        int dx[] = {0,0,-1,1}, dy[] = {1,-1,0,0};
        q.offer(str);
        map.put(str , 0);   //记录该状态和达到改状态的交换次数
        while(!q.isEmpty())
        {
            String tmp = q.poll();
            int dist = map.get(tmp);

            int k = tmp.indexOf('x');
            int x = k / 3 , y = k % 3;  //找到'x'的坐标(x,y)


            for(int i = 0 ; i < 4 ; i ++)
            {
                int px = x+dx[i] , py = y + dy[i];
                if(px < 0 || px >= 3 || py < 0 || py >= 3 )continue;
                //将(px,py)与(x,y)交换
                char ch[] = tmp.toCharArray();
                char c = ch[k];
                ch[k] = ch[px * 3 + py];
                ch[px * 3 + py] = c;


                String new_str = String.valueOf(ch);

                if(new_str.equals(end)) return dist + 1;

                if(!map.containsKey(new_str)){

                    map.put(new_str , dist + 1);
                    q.offer(new_str);
                } 


            }
        }
        return -1;
    }
    public static void main(String[] args) throws IOException
    {
        String str = in.readLine().replaceAll(" ","");

        String end = "12345678x";
        System.out.println(bfs(str,end));


    }
}