#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
#define fi first
#define se second
template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = 0;
//---------------------------------//

int main() {
	int N;
	cin >> N;
	
	vector<int> S(N), T(N);
	REP(i, N) scanf("%d", &S[i]);
	REP(i, N) scanf("%d", &T[i]);
	
	vector<vector<int>> ans(N, vector<int>(N));
	bool yoko = false, tate = false;
	REP(i, N) {
		if (S[i] == 2) { REP(j, N) ans[i][j] = 1; yoko = true; }
		if (T[i] == 2) { REP(j, N) ans[j][i] = 1; tate = true; }
	}
	
	int ansc = 0;
	if (!yoko || !tate) {
		if (yoko) { REP(i, N) if (S[i] == 1) ++ansc; }
		else if (tate) { REP(i, N) if (T[i] == 1) ++ansc; }
		else {
			int a[2] {};
			REP(i, N) a[0] += S[i] == 1;
			REP(i, N) a[1] += T[i] == 1;
			ansc = max(a[0], a[1]);
		}
	}
	
	REP(i, N) REP(j, N) ansc += ans[i][j];
	cout << ansc << endl;
	return 0;
}