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

public class Main {
    static int N = 200003;
    static int bound = (int) 1e9 + 1;
    static int[] h = new int[N];
    static int[] ha = new int[N];
    static long mod = Long.MAX_VALUE;
    static int pre = 1331;

    static int find(int x) {
        int k = (x % N + N) % N;
        while (h[k] != bound && h[k] != x) {
            k++;
            if (k == N)
                k = 0;
        }
        return k;
    }

    static int bfs(String start, String end) {
        Queue<pairs> q = new LinkedList<>();
        q.add(new pairs(start, 0));
        int[] dx = { -1, 0, 1, 0 }, dy = { 0, 1, 0, -1 };
        while (!q.isEmpty()) {
            pairs s = q.poll();
            hash(s.string);
            h[find(ha[9])] = ha[9];
            if (s.string.equals(end)) {
                return s.distance;
            }
            String str = s.string;
            int k = str.indexOf('x');
            int x = k / 3, y = k % 3;
            for (int i = 0; i < 4; i++) {
                int a = x + dx[i];
                int b = y + dy[i];
                if (a >= 0 && a < 3 && b >= 0 && b < 3) {
                    char[] c = str.toCharArray();
                    swap(c, k, a * 3 + b);
                    String str2 = new String(c);
                    hash(str2);
                    if (h[find(ha[9])] == bound) {
                        q.add(new pairs(str2, s.distance+1));

                    }
                }
            }
        }
        return -1;
    }

    static void hash(String str) {
        int len = str.length();
        for (int i = 1; i <= len; i++) {
            ha[i] = (int) (ha[i - 1] * pre + (str.charAt(i - 1)) % mod);
        }
    }

    static void swap(char[] s, int x, int x1) {
        char temp = s[x];
        s[x] = s[x1];
        s[x1] = temp;
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] s = br.readLine().split(" ");
        String start = "";
        for (String x : s) {
            start += x;
        }
        String end = "12345678x";
        Arrays.fill(h, bound);
        System.out.println(bfs(start, end));

    }
}

class pairs {
    String string;
    int distance;

    public pairs(String s, int x) {
        this.string = s;
        this.distance = x;
    }

}