#include <bits/stdc++.h>
#define rep(i, l, r) for (int i = (l); i < (r); i++)
using namespace std;

typedef long long ll;

int main() {
    int N;
    cin >> N;
    vector<int> A(2 * N + 1), B(2 * N - 1, 0);
    rep(i, 0, 2 * N + 1) cin >> A[i];
    rep(i, 0, 2 * N - 1) {
        if (A[i + 1] == (A[i] + 1) % 3 && A[i + 2] == (A[i] + 2) % 3) B[i] = 1;
        if (A[i + 1] == (A[i] + 2) % 3 && A[i + 2] == (A[i] + 1) % 3) B[i] = 2;
    }
    //rep(i, 0, 2 * N - 1) cout << B[i] << " "; cout << endl;
    bool f = true;
    rep(i, 0, 2 * N - 1) {
        if (i % 2 == 1 && B[i] != 0) f = false;
        if (i % 2 == 0 && i < 2 * N - 3 && B[i] + B[i + 2] != 3) f = false;
    }
    if (f) cout << B.back() << endl;
    else cout << "0\n";
}