import java.util.Scanner;

public class Main{

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

        int n = Integer.parseInt(scan.nextLine());
        String[] a1 = scan.nextLine().split(" ");
        String[] a2 = scan.nextLine().split(" ");

        int max = 0;
        for(int i=0; i<n; i++){
            int cnt = 0;
            for(int j=0; j<=i; j++){
                cnt += Integer.parseInt(a1[j]);
            }
            for(int j=i; j<n; j++){
                cnt += Integer.parseInt(a2[j]);
            }
            if(cnt > max) max = cnt;
        }

        System.out.println(max);

        scan.close();
    
    }

}
/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