import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[][] a = new int[2][n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                a[i][j] = Integer.parseInt(sc.next());
            }
        }
        int ans = 0;
        for (int i = 0; i < n; i++) {
            int temp = 0;
            for (int j = 0; j <= i; j++) {
                temp += a[0][j];
            }
            for (int j = i; j < n; j++) {
                temp += a[1][j];
            }
            ans = Math.max(ans, temp);
        }
        System.out.println(ans);
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz