#include<iostream>
#include<cmath>
#include<string>
#include<queue>
#include<map>
using namespace std;

#define N 3
#define N2 9

struct Puzzle
{
  int f[N2];
  int space;
  string path;

  bool operator < (const Puzzle &p) const
  {
    for(int i=0;i<N2;i++)
      {
	if(f[i]==p.f[i]) continue;
	return f[i] > p.f[i];
      }
    return false;
  }
};


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

bool isTarget(Puzzle p)
{
  for(int i=0;i<N2;i++)
  
    if(p.f[i]!=(i+1)) return false;
  return true;
}

string bfs(Puzzle s)
{
  queue<Puzzle>Q;
  map<Puzzle, bool>V;
  Puzzle u,v;
  s.path="";
  Q.push(s);
  V[s]=true;

  while(!Q.empty())
    {
      u=Q.front();Q.pop();
      if(isTarget(u)) return u.path;
      int sx=u.space/N;
      int sy=u.space%N;
      for(int r=0;r<4;r++)
	{
	  int tx=sx+dx[r];
	  int ty=sy+dy[r];
	  if(tx<0||ty<0||tx>=N||ty>=N) continue;
	  v=u;
	  swap(v.f[u.space],v.f[tx*N+ty]);
	  v.space=tx*N+ty;
	  if(!V[v])
	    {
	      V[v]=true;
	      v.path += dir[r];
	      Q.push(v);
	    }
	}
    }
  return "unsolvable";
}

int main()
{
  Puzzle in;

  for(int i=0;i<N2;i++)
    {
      cin>>in.f[i];
      if(in.f[i]==0)
	{
	  in.f[i]=N2;
	  in.space=i;
	}
    }
  string ans=bfs(in);
  cout<<ans.size()<<endl;

  return 0;
}
	    

