#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;

int main()
{
    int n; cin>>n;
    int a[200020];
    for(int i=0; i<2*n+1; i++) cin>>a[i];
    int a1[2][4]={{0,2,1,2},{0,1,2,1}};
    bool b1=1, b2=1;
    for(int i=1; i<2*n+1; i++){
        int x=(a[i]-a[0]+3)%3;
        if(x!=a1[n%2][i%4]){
            b1=0;
        }
        if(x!=a1[(n%2)^1][i%4]){
            b2=0;
        }
    }
    if(b1)cout<<1<<endl;
    else if(b2)cout<<2<<endl;
    else cout<<0<<endl;
    return 0;
    set<vector<int>> st;
    auto dfs=[&](auto dfs, vector<int> &v)->void{
        if(v.size()==2*n+1){
            auto w=v;
            for(int i=0; i<n; i++){
                vector<int> w1;
                for(int j=1; j<(int)w.size()-1; j++){
                    if((w[j]-w[j-1]+3)%3==1 && (w[j+1]-w[j]+3)%3==1){
                        w1.push_back(1);
                    }else if((w[j]-w[j-1]+3)%3==2 && (w[j+1]-w[j]+3)%3==2){
                        w1.push_back(2);
                    }else{
                        w1.push_back(0);
                    }
                }
                swap(w, w1);
            }
            if(w[0]==2){
                for(int i=0; i<2*n+1; i++) cout<<v[i]<<" ";
                cout<<endl;
                st.insert(v);
            }
            return;
        }
        for(int i=0; i<3; i++){
            v.push_back(i);
            dfs(dfs, v);
            v.pop_back();
        }
    };
    vector<int> v0;
    dfs(dfs, v0);
    cout<<st.size()<<endl;
    

    return 0;
}