import java.util.*;

public class Main {
    public static int bfs(String start) {
        String end = "12345678x";
        Queue<String> q = new LinkedList<>();
        Map<String, Integer> d = new HashMap<>();

        q.offer(start);
        d.put(start, 0);

        int[] dx = {-1,1,0,0};
        int[] dy = {0,0,-1,1};

        while(!q.isEmpty()) {
            String t = q.poll();
            if(t.equals(end)) return d.get(end);

            int dis = d.get(t);
            int k = t.indexOf('x');

            for(int i = 0 ;i < 4; i++) {
                int x = k / 3 + dx[i];
                int y = k % 3 + dy[i];
                if (x >= 0 && y >= 0 && x < 3 && y < 3) {
                    char[] chs = t.toCharArray();
                    char tmp = chs[k];
                    chs[k] = chs[x * 3 + y];
                    chs[x * 3 + y] = tmp;

                    String newStr = String.valueOf(chs);
                    if (d.get(newStr) == null) {
                        d.put(newStr, dis + 1);
                        q.offer(newStr);
                    }
                }
            }
        }

        return -1;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String start = "";
        for(int i = 0; i < 9;i++) {
            start += sc.next();
        }
        System.out.println(bfs(start));
    }
}