#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <unordered_set>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif
#define GET_MACRO(_1, _2, _3, NAME, ...) NAME
#define _rep(i, n) _rep2(i, 0, n)
#define _rep2(i, a, b) for(int i = (int)(a); i < (int)(b); i++)
#define rep(...) GET_MACRO(__VA_ARGS__, _rep2, _rep)(__VA_ARGS__)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
using i64 = long long;
template<class T, class U>
bool chmin(T& a, const U& b) { return (b < a) ? (a = b, true) : false; }
template<class T, class U>
bool chmax(T& a, const U& b) { return (b > a) ? (a = b, true) : false; }

template<typename T>istream& operator>>(istream&i,vector<T>&v){rep(j,v.size())i>>v[j];return i;}
template<typename T>string join(vector<T>&v){stringstream s;rep(i,v.size())s<<' '<<v[i];return s.str().substr(1);}
template<typename T>ostream& operator<<(ostream&o,vector<T>&v){if(v.size())o<<join(v);return o;}
template<typename T>string join(vector<vector<T>>&vv){string s="\n";rep(i,vv.size())s+=join(vv[i])+"\n";return s;}
template<typename T>ostream& operator<<(ostream&o,vector<vector<T>>&vv){if(vv.size())o<<join(vv);return o;}

int main(){
    int n;
    cin >> n;
    vector<int> a(2 * n + 1);
    cin >> a;
    rep(i, 2 * n){
        if (a[i] == a[i + 1]){
            cout << 0 << endl;
            return 0;
        }
    }
    vector<int> nx;
    set<tuple<int, int, int>> one = {{0, 1, 2}, {1, 2, 0}, {2, 0, 1}};
    set<tuple<int, int, int>> two = {{2, 1, 0}, {0, 2, 1}, {1, 0, 2}};
    rep(i, 2 * n - 1){
        int x = a[i], y = a[i + 1], z = a[i + 2];
        if (one.count({x, y, z})) nx.push_back(1);
        else if (two.count({x, y, z})) nx.push_back(2);
        else nx.push_back(0);
    }
    int nn = nx.size();
    if (nx[0] == 0 && nx.back() == 0){
        cout << 0 << endl;
        return 0;
    }
    rep(i, nn - 1){
        if (nx[i] == nx[i + 1]){
            cout << 0 << endl;
            return 0;
        }
        if (i + 2 < nn && nx[i] > 0 && nx[i + 2] == nx[i]){
            cout << 0 << endl;
            return 0;
        }
    }
    cout << nx.back() << endl;
}