（通过老师的测试点知道部分多了1）

#include<bits/stdc++.h>
using namespace std;
map<string,bool> l;
string que[1000000];
short qu[1000000];
short sh[1000000];

int a0(string s){
	for(int i=0;i<9;i++)
		if(s[i]=='0')return i;
	return 0;
}

int main(){
//	freopen("tai.in","r",stdin);
//	freopen("tai.out","w",stdout);
	string s;
	cin>>s;
	l[s]=1;
	que[0]=s;
	qu[0]=a0(s);
	int head=0,tail=0;
	sh[0]=0;
	while(head<=tail){
	//	cout<<que[head]<<endl;
	//	getchar();
		if(que[head]=="123804765"){
			cout<<sh[head];
			return 0;
		}
		int f=qu[head];
		if(f%3!=2){//向右 
			swap(que[head][f],que[head][f+1]);
			if(!l[que[head]])tail++,que[tail]=que[head],qu[tail]=f+1,l[que[head]]=1;
			swap(que[head][f],que[head][f+1]);
			sh[tail]=sh[head]+1;
		}
		if(f%3){//向左 
			swap(que[head][f],que[head][f-1]);
			if(!l[que[head]])tail++,que[tail]=que[head],qu[tail]=f-1,l[que[head]]=1;
			swap(que[head][f],que[head][f-1]);
			sh[tail]=sh[head]+1;
		}
		if(f>2){//向上 
			swap(que[head][f],que[head][f-3]);
			if(!l[que[head]])tail++,que[tail]=que[head],qu[tail]=f-3,l[que[head]]=1;
			swap(que[head][f],que[head][f-3]);
			sh[tail]=sh[head]+1;
		}
		if(f<6){//向下 
			swap(que[head][f],que[head][f+3]);
			if(!l[que[head]])tail++,que[tail]=que[head],qu[tail]=f+3,l[que[head]]=1;
			swap(que[head][f],que[head][f+3]);
			sh[tail]=sh[head]+1;
		}
		head++;
	}
}