import java.util.*;

public class Main {

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        int[] lineOne = new int[n];
        int[] lineTwo = new int[n];

        for (int i = 0; i < n; i++) {
            lineOne[i] = sc.nextInt();
        }
        for (int i = 0; i < n; i++) {
            lineTwo[i] = sc.nextInt();
        }

        int max = 0;
        for (int i = 0; i < n; i++) {
            int sum = 0;
            for (int j = 0; j < n; j++) {
                if (j <= i) {
                    sum += lineOne[j];
                }
                if (j >= i) {
                    sum += lineTwo[j];
                }
            }
            max = Math.max(max, sum);
        }
        System.out.println(max);
    }

}
/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