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

using namespace std;

string ed = "12345678x";

int bfs(string start)
{
    queue<string> q;
    unordered_map<string , int> d;

    q.push(start);
    d[start] = 0;

    int dx[4] = {-1 , 0 , 1 , 0} , dy[4] = {0 , 1 , 0 , -1};
    while(q.size())
    {
        auto t = q.front();
        q.pop();

        if(t == ed) return d[t];

        int k = t.find('x');
        int a = k / 3 , b = k % 3;
        int dis = d[t];
        for(int i = 0 ; i < 4 ; i++)
        {
            int x = a + dx[i] , y = b + dy[i];
            if(x >= 0 && x < 3 && y >= 0 && y < 3){
                swap(t[k] , t[3*x+y]);

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

                swap(t[k] , t[3*x+y]);
            }
        }
    }

    return -1;
}

int main()
{
    string state;
    char op[2];
    for(int i = 0 ; i < 9 ; i++)
    {
        cin >> op;
        state += *op;
    }
    cout << bfs(state) << endl;


    return 0;
}