#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000000000

vector<int> get(vector<int> a){
	vector<int> b(a.size()-1);
	rep(i,a.size()-1){
		int d = a[i+1] - a[i];
		d %=3 ;
		if(d<0)d += 3;
		b[i] = d;
	}
	
	vector<int> ret;
	rep(i,b.size()-1){
		if(b[i]!=0&&b[i]==b[i+1])ret.push_back(b[i]);
		else ret.push_back(0);
	}
	return ret;
	
}

int main(){
	
	int n;
	cin>>n;
	
	vector<int> a(n*2+1);
	rep(i,a.size())cin>>a[i];
	
	a = get(a);
	if(a.size()==1){
		cout<<a[0]<<endl;
		return 0;
	}
	rep(i,a.size()){
		if(i%2==1&&a[i]!=0){
			cout<<0<<endl;
			return 0;
		}
		if(i%2==0){
			if(a[i]==0||(i+2<a.size()&&a[i]==a[i+2])){
				cout<<0<<endl;
				return 0;
			}
		}
	}
	
	int ans = a[0];
	while(a.size()!=1){
		rep(i,2)a.pop_back();
		ans ^= 3;
	}
	cout<<ans<<endl;
	
	
	
	return 0;
}