#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------

int N;
int A[202020];
int B[202020];

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N;
	FOR(i,2*N+1) {
		cin>>A[i];
	}
	FOR(i,2*N-1) {
		if((A[i]+1)%3==A[i+1]&&(A[i+1]+1)%3==A[i+2]) {
			B[i]=1;
		}
		if((A[i]+2)%3==A[i+1]&&(A[i+1]+2)%3==A[i+2]) {
			B[i]=2;
		}
	}
	N=2*N-1;
	FOR(i,N) {
		if(i%2==1) {
			if(B[i]) {
				cout<<0<<endl;
				return;
			}
		}
		else {
			if(B[i]==0) {
				cout<<0<<endl;
				return;
			}
			if(i&&B[i]==B[i+2]) {
				cout<<0<<endl;
				return;
			}
		}
	}
	x=B[0];
	while(N>1) {
		x=3^x;
		N-=2;
	}
	cout<<x<<endl;
	
	
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}