#include<iostream>
#include<cstring>
#include<queue>
#include<unordered_map>   
using namespace std;


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

unordered_map<string, int> cnt;

int bfs(){

    queue<string> q;
    q.push(s);
    cnt[s] = 0;      // map可以用[]创建新内容；
    string end = "12345678x";
    while(q.size()){
        auto t = q.front();
        q.pop();
        if(t == end) return cnt[end];

        int distance = cnt[t];
        int k = t.find('x');
        for(int i = 0; i < 4; i++){
            int x = k/3 + dx[i];     //一维转二维
            int y = k%3 + dy[i];
            if(x >= 0 && x < 3 && y >= 0 && y < 3){
                int newk = x*3 + y;
                swap(t[k], t[newk]);
                //cout<< t << endl ;
                if(!cnt.count(t)){
                    q.push(t);
                    cnt[t] = distance + 1;
                }
                swap(t[k], t[newk]);
            }

        }

    }

    return -1;
}


int main(){
    char c;                       //先读入字符，然后在拼接给s;
    for(int i = 0; i < 9; i++) {
        cin>> c; 
        s += c;
    }

    //cout<<s<<endl;
    cout<< bfs() ;

    return 0;
}