#include <bits/stdc++.h>

#define F first
#define S second
#define MP make_pair
#define pb push_back
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define LCM(a, b) (a) / __gcd((a), (b)) * (b)
#define CEIL(a, b) (a)/(b)+(((a)%(b))?1:0)
#define log_2(a) (log((a)) / log(2))
#define ln '\n'

using namespace std;
using LL = long long;
using ldouble = long double;
using P = pair<int, int>;
using LP = pair<LL, LL>;

static const int INF = INT_MAX;
static const LL LINF = LLONG_MAX;
static const int MIN = INT_MIN;
static const LL LMIN = LLONG_MIN;
static const int MOD = 1e9 + 7;
static const int SIZE = 200005;

const int dx[] = {0, -1, 1, 0};
const int dy[] = {-1, 0, 0, 1};

vector<LL> Div(LL n) {
    vector<LL> ret;
    for(LL i = 1; i * i <= n; ++i) {
        if(n % i == 0) {
            ret.pb(i);
            if(i * i != n) ret.pb(n / i);
        }
    }
    sort(all(ret));
    return ret;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int N;
    cin >> N;

    int mat[505][505];
    bool fc[505] = {};
    bool fr[505] = {};
    for(int i = 1; i <= N; ++i) {
        for(int j = 1; j <= N; ++j) {
            mat[i][j] = -1;
        }
    }

    vector<int> s(N + 1), t(N + 1);
    for(int i = 1; i <= N; ++i) {
        cin >> s[i];
        if(s[i] == 2) s[i] = 1;
        else if(s[i] == 1) s[i] = 2;
    }
    for(int i = 1; i <= N; ++i) {
        cin >> t[i];
        if(t[i] == 2) t[i] == 1;
        else if(t[i] == 1) t[i] = 2;
    }

    int res = 0;
    for(int i = 1; i <= N; ++i) {
        if(s[i] == 0 || s[i] == 1) {
            for(int j = 1; j <= N; ++j) {
                if(mat[i][j] == -1) res += s[i];
                mat[i][j] = s[i];
                if(s[i] == 1) fr[j] = true;
            }
        }
    }

    for(int i = 1; i <= N; ++i) {
        if(t[i] == 0 || t[i] == 1) {
            for(int j = 1; j <= N; ++j) {
                if(mat[j][i] == -1) res += t[i];
                mat[j][i] = t[i];
                if(t[i] == 1) fc[j] = true;
            }
        }
    }

    for(int i = 1; i <= N; ++i) {
        if(s[i] != 2) continue;
        int pos = -1;
        for(int j = 1; j <= N; ++j) {
            if(mat[i][j] == 1) {
                pos = -1;
                break;
            }
            if(t[j] == 2 && mat[i][j] == -1 && !fr[j]) {
                ++res;
                mat[i][j] = 1;
                fr[j] = true;
                pos = -1;
                break;
            }
            if(mat[i][j] == -1) {
                pos = j;
            }
        }
        if(pos != -1) {
            mat[i][pos] = 1;
            ++res;
        }
    }

    for(int i = 1; i <= N; ++i) {
        if(t[i] != 2) continue;
        bool f = false;
        for(int j = 1; j <= N; ++j) {
            f = (f || (mat[j][i] == 1));
        }
        if(!f) ++res;
    }
    cout << res << endl;

    /*
    for(int i = 1; i <= N; ++i) {
        for(int j = 1; j <= N; ++j) {
            cout << mat[i][j] << " ";
        }
        cout << endl;
    }
    */
    return 0;
}