#include <iostream>
#include <cstdio>
#include <queue>
#include <unordered_map>

using namespace std;

int dx[4] = {0,0,-1,1},dy[4] = {-1,1,0,0};

int bfs(string start)
{
    string end = "12345678x";
    queue<string> q;
    unordered_map<string,int> dis;

    q.push(start);
    dis[start] = 0;
    while(!q.empty())
    {
        string t = q.front();
        q.pop();
        int d = dis[t];

        if(t == end)
            return d;

        int p = t.find('x');
        int x = p / 3,y = p % 3;
        for(int i = 0;i < 4;i ++)
        {
            int xx = x + dx[i],yy = y + dy[i];
            if(xx >= 0 && xx < 3 && yy >= 0 && yy < 3)
            {
                swap(t[p],t[xx * 3 + yy]);

                if(!dis.count(t))
                {
                    dis[t] = d + 1;
                    q.push(t);
                }

                swap(t[p],t[xx * 3 + yy]);
            }
        }
    }

    return -1;
}

int main()
{
    string start;
    for(int i = 0;i < 9;i ++)
    {
        char c;
        cin >> c;

        start += c;
    }

    cout << bfs(start);

    return 0;
}