#define _USE_MATH_DEFINES
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <clocale>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

#define IOS ios::sync_with_stdio(false); cin.tie(0);
#define FOR(i, s, n) for(int i = (s), i##_len=(n); i < i##_len; ++i)
#define FORS(i, s, n) for(int i = (s), i##_len=(n); i <= i##_len; ++i)
#define VFOR(i, s, n) for(int i = (s); i < (n); ++i)
#define VFORS(i, s, n) for(int i = (s); i <= (n); ++i)
#define REP(i, n) FOR(i, 0, n)
#define REPS(i, n) FORS(i, 0, n)
#define VREP(i, n) VFOR(i, 0, n)
#define VREPS(i, n) VFORS(i, 0, n)
#define RFOR(i, s, n) for(int i = (s), i##_len=(n); i >= i##_len; --i)
#define RFORS(i, s, n) for(int i = (s), i##_len=(n); i > i##_len; --i)
#define RREP(i, n) RFOR(i, n, 0)
#define RREPS(i, n) RFORS(i, n, 0)
#define ALL(v) (v).begin(), (v).end()
#define SORT(v) sort(ALL(v))
#define RSORT(v) sort(ALL(v), greater<decltype(v[0])>())
#define SZ(x) ((int)(x).size())
#define PB push_back
#define MP make_pair
#define MT make_tuple
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(ALL(v)), v.end())

using ll = long long;
using Pi_i = pair<int, int>;
using VB = vector<bool>;
using VC = vector<char>;
using VD = vector<double>;
using VI = vector<int>;
using VLL = vector<ll>;
using VS = vector<string>;
using VSH = vector<short>;

const int MOD = 1000000007;
const int INF = 1000000000;
const int NIL = -1;

template<class T, class S>
bool chmax(T &a, const S &b){
    if(a < b){
        a = b; return true;
    }
    return false;
}
template<class T, class S>
bool chmin(T &a, const S &b){
    if(b < a){
        a = b; return true;
    }
    return false;
}


const int N = 3;
const int NN = N * N;
struct Puzzle{
    int num[NN] = {};
    int space = NIL;
    string path;

    bool operator<(const Puzzle &b) const{
        REP(i, NN){
            if(num[i] == b.num[i]) continue;
            return num[i] < b.num[i];
        }
        return false;
    }
};

int dx[4] = {-1, 0, 0, 1};
int dy[4] = {0, -1, 1, 0};
char dir[4] = {'u', 'l', 'r', 'd'};

bool isGoal(Puzzle& p){
    REP(i, NN)
        if(p.num[i] != i+1) return false;
    return true;
}

string bfs(Puzzle s){
    queue<Puzzle> que;
    map<Puzzle, bool> mp;
    s.path = "";
    que.push(s);
    mp[s] = true;

    while(!que.empty()){
        Puzzle p = que.front(); que.pop();
        if(isGoal(p)) return p.path;
        int px = p.space / N;
        int py = p.space % N;
        REP(i, 4){
            int nx = px + dx[i];
            int ny = py + dy[i];
            if(nx<0 || ny<0 || nx>=N || ny>=N)
                continue;
            Puzzle q = p;
            swap(q.num[q.space], q.num[nx*N + ny]);
            q.space = nx*N + ny;
            if(!mp[q]){
                mp[q] = true;
                q.path += dir[i];
                que.push(q);
            }
        }
    }
    return "";
}

int main(){
    Puzzle in;
    REP(i, NN){
        cin >> in.num[i];
        if(in.num[i] == 0){
            in.num[i] = NN;
            in.space = i;
        }
    }
    string ans = bfs(in);
    cout << ans.length() << endl;
    return 0;
}



Measured memory_bytes: 30540