#include<cstdio>
#include<algorithm>
using namespace std;
const int maxn = 2000 + 1;

int solve(int n, int *a, int *b)
{
	int dp[maxn] = {0};
	
	for (int i = 1; i <= n; ++i)
	{
		int dg = dp[0];
		for (int j = 1; j <= n; ++j)
		{
			int val = max({dg + min(a[i], b[j]), dp[j], dp[j - 1]});
			dg = dp[j];
			dp[j] = val;
		}
	}
	return dp[n];
}

int main()
{
	int n;
	int a[maxn], b[maxn];
	scanf("%d", &n);
	for (int i = 1; i <= n; ++i)
	{
		scanf("%d", &a[i]);
	}
	for (int j = 1; j <= n; ++j)
	{
		scanf("%d", &b[j]);
	}
	printf("%d\n", solve(n, a, b));
	return 0;
}