#include<stdio.h>
#include<bits/stdc++.h>
#define N 1000010
#define MOD 998244353
#define esp 1e-8
#define INF 999999999999999999
#define LL long long
#define rep(i,a,b,g) for(LL i=a;i<=b;i+=g)
#define rem(i,a,b,g) for(LL i=a;i>=b;i-=g)
#define repn(i,a,b,g) for(LL i=a;i<b;i+=g)
#define remn(i,a,b,g) for(LL i=a;i>b;i-=g)
#define pll pair<LL,LL>
#define mkp(x,y) make_pair(x,y)
#define i128 __int128
#define lowbit(x) ((x)&(-(x)))
#define lc (u<<1)
#define rc (u<<1|1)
using namespace std;
void read(i128 &x)
{
	i128 f=1;
	x=0;
	char ch=getchar();
	while(ch<'0'||ch>'9')
	{
		if(ch=='-')f=-1;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9')
	{
		x=x*10+ch-'0';
		ch=getchar();
	}
	x*=f;
}
void writing(i128 x)
{
	if(x>=10)writing(x/10);
	putchar(x%10+'0');
}
void write(i128 x)
{
	if(x<0)
	{
		cout<<'-';
		x=-x;
	}
	writing(x);
}
char ch[20];
LL en[4][4]=
{
    {0,0,0,0},
    {0,1,2,3},
    {0,8,0,4},
    {0,7,6,5}
};
LL a[10][10],sd;
bool don;
LL dx[]={0,1,-1,0};
LL dy[]={1,0,0,-1};
bool che()
{
	rep(i,1,3,1)
	{
		rep(j,1,3,1)
		{
			if(en[i][j]!=a[i][j])return 0;
		}
	}
	return 1;
}
bool gg(LL sp)
{
	LL sum=0;
	rep(i,1,3,1)
	{
		rep(j,1,3,1)
		{
			if(en[i][j]!=a[i][j])
			{
				sum++;
				if(sum+sp>sd)
				{
					return 0;
				}
			}
		}
	}
	return 1;
}
void idastar(LL sp,LL x,LL y,LL bef)
{
	if(sp==sd)
	{
		if(che())don=1;
		return;
	}
	repn(i,0,4,1)
	{
		LL nx=x+dx[i],ny=y+dy[i];
		if(nx<1||nx>3||ny<1||ny>3||bef+i==3)continue;
		swap(a[x][y],a[nx][ny]);
		if(gg(sp)&&!don)
		{
			idastar(sp+1,nx,ny,i);
		}
		swap(a[x][y],a[nx][ny]);
	}
}
int main()
{
	LL x,y;
	cin>>ch;
	repn(i,0,9,1)
    {
        a[i/3+1][i%3+1]=ch[i]-'0';
        if(ch[i]-'0'==0)
        {
        	x=i/3+1;
			y=i%3+1;
		}
    }
    if(che())
    {
    	cout<<0<<endl;
	}
	else
	{
		while(1)
		{
			sd++;
			idastar(0,x,y,-1);
			if(don)
			{
				cout<<sd<<endl;
				break;
			}
		}
	}
	return 0;
}