#include <iostream>
#include <vector>
#include <deque> 
#include <set>
#include <utility>
using namespace std;
set<vector<int>> visited;
//这里默认九宫格 
void swapUp(vector<int>& _v, int _i){
	if(_i == 0 || _i == 1 || _i ==2 ) return;
	swap(_v[_i], _v[_i - 3]);
}
void swapDown(vector<int>& _v, int _i){
	if(_i == 6 || _i == 7 || _i ==8 ) return;
	swap(_v[_i], _v[_i + 3]);
}
void swapLeft(vector<int>& _v, int _i){
	if(_i == 0 || _i == 3 || _i ==6 ) return;
	swap(_v[_i], _v[_i - 1]);
}
void swapRight(vector<int>& _v, int _i){
	if(_i == 2 || _i == 5 || _i ==8 ) return;
	swap(_v[_i], _v[_i + 1]);
}
//pos -> 白格位置 
int bfs(vector<int> _aim, vector<int> _v){
    deque<pair<vector<int>, int>> q;
    q.push_back({_v, 0});
    visited.insert(_v);

    while(!q.empty()){
    	auto tmp = q.front(); q.pop_front();
        vector<int> tmpv = tmp.first;
        int step = tmp.second;
    	
    	if(tmpv == _aim) return step;
    	
    	int x;
		for(int i = 0; i < tmpv.size(); i++){
			if(tmpv[i] == 0) {
				x = i;
				break;
			}
		} 
    	// 上
        if(x >= 3){
            vector<int> tmps = tmpv;
            swapUp(tmps, x);
            if(!visited.count(tmps)){
                visited.insert(tmps);
                q.push_back({tmps, step + 1});
            }
        }

        // 下
        if(x <= 5){
            vector<int> tmps = tmpv;
            swapDown(tmps, x);
            if(!visited.count(tmps)){
                visited.insert(tmps);
                q.push_back({tmps, step + 1});
            }
        }

        // 左
        if(x % 3 != 0){
            vector<int> tmps = tmpv;
            swapLeft(tmps, x);
            if(!visited.count(tmps)){
                visited.insert(tmps);
                q.push_back({tmps, step + 1});
            }
        }

        // 右
        if(x % 3 != 2){
            vector<int> tmps = tmpv;
            swapRight(tmps, x);
            if(!visited.count(tmps)){
                visited.insert(tmps);
                q.push_back({tmps, step + 1});
            }
        }
    }
    return -1; // 无解
}

int main(){
	int n;
	cin >> n;
	vector<int> arr(n, -1);
	vector<int> aim(n, -1); 
	int pos;
	for(int i = 0; i < n; i++){
		cin >> arr[i];
		if(arr[i] == 0) pos = i;
	}
	for(int i = 0; i < n; i++){
		cin >> aim[i];
	}
	cout << bfs(aim, arr) << endl;
	
	return 0;
}
/*
9
2 6 4 1 3 7 0 5 8
8 1 5 7 3 6 4 0 2
*/