#include <bits/stdc++.h>
using namespace std;

int N, G[2][101];

int main(){
	int large = 0;
	scanf("%d", &N);
	for(int i = 0; i < 2; i++)
		for(int j = 1; j <= N; j++)
			scanf("%d", &G[i][j]), G[i][j] += G[i][j - 1];
	for(int i = 1; i <= N; i++) large = max(large, G[0][i] + G[1][N] - G[1][i - 1]);
	printf("%d\n", large);
	return 0;
}
