#include <bits/stdc++.h>
using namespace std;
#define rep2(i,m,n) for (int i = (m); i < (n); ++i)
#define rep(i,n) rep2(i,0,n)
#define debug(x) cerr << x << endl
typedef long long int ll;
typedef long double ld;
typedef pair<ll, ll> P;
template<typename T> struct V : vector<T> { using vector<T>::vector; };
V() -> V<int>;
V(size_t) -> V<int>;
template<typename T> V(size_t, T) -> V<T>;
template<typename T> vector<T> make_vec(size_t n, T a) { return vector<T>(n, a); }
template<typename... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec(ts...))>(n, make_vec(ts...)); }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
template<typename T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; }
template<typename T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; }
const int INF = 1e9;
const ll LINF = 1LL<<61;
const ll MOD = 1000000007;

int main()
{
    int N;
    cin >> N;
    V S(N), T(N); //row, col
    V fs(N), ft(N); //条件を満たしているか
    rep(i,N) cin >> S[i];
    rep(i,N) cin >> T[i];
    auto mat = make_vec(N, N, 0);
    rep(i,N)
    {
        if(S[i] == 2)
        {
            rep(j,N) mat[i][j] = 1;
            fs[i] = true;
        }
        if(S[i] == 0)
        {
            fs[i] = true;
        }
        if(T[i] == 2)
        {
            rep(j,N) mat[j][i] = 1;
            ft[i] = true;
        }
        if(T[i] == 0)
        {
            ft[i] = true;
        }
    }

    rep(i,N) rep(j,N)
    {
        if(fs[i] == false && ft[j] == false)
        {
            mat[i][j] = 1;
            fs[i] = true;
            ft[j] = true;
        }
    }

    rep(i,N) rep(j,N)
    {
        if(S[i] == 1 && mat[i][j] == 1) fs[i] = true;
        if(T[j] == 1 && mat[i][j] == 1) ft[j] = true;
    }

    int ans = 0;
    rep(i,N) rep(j,N) ans += mat[i][j];
    rep(i,N) if(fs[i] == false) ans++;
    rep(i,N) if(ft[i] == false) ans++;
    cout << ans << endl;

    return 0;
}