#include <cstdio>
#include <queue>
#include <set>
#include <queue>
using namespace std;

using ll = long long;
int dy[4] = {1,0,-1,0}, dx[4] = {0,1,0,-1};
int shift[4] = {-12,-4,12,4};

int main() {
    ll start = 0, dest = 0;
    for(int i=0; i<9; ++i) {
        ll a;
        scanf("%lld",&a);
        start += (a<<i*4);
    }

    for(int i=1; i<9; ++i)  {
        dest += ((ll)i<<(4 * (i-1)));
    }

    set<ll> visited;
    queue<ll> q;
    q.push(start);
    int ret = 0;
    while(!q.empty()) {
        ll qs = q.size();
        while(qs--) {
            ll cur = q.front();
            q.pop();
            if(cur == dest) {
                printf("%d\n",ret);
                return 0;
            }
            ll pos0 = 0;
            for(;cur & (15LL << pos0 * 4); pos0++);
            ll y = pos0/3, x = pos0%3;
//            printf("%lld %lld\n",r,c);
            for(int i=0; i<4; ++i) {
                ll ny = y + dy[i], nx = x + dx[i];
                if(ny < 0 || ny >= 3 || nx < 0 || nx >= 3) continue;
                //temp: 0으로 만들고자 하는 위치의 cur의 bit
                ll temp = cur & (15LL <<(ny*3+nx)*4);
                //cur의 0000 부분과 다음 상태의 0000부분이 0000인 상태
                ll next = cur - temp;
                //
                if(shift[i] > 0) temp <<= shift[i];
                else temp >>= -shift[i];

                next += temp;
                if(visited.find(next) == visited.end()) {
                    visited.insert(next);
                    q.push(next);
                }
            }
        }
        ++ret;
    }
    puts("-1");
}