import java.util.Scanner;

class Main {
	public static void main(String[] $) {
		Scanner sc = new Scanner(System.in);
		int n=sc.nextInt();
		int[][] a=new int[2][n];
		int max=0;
		for(int i=0;i<2;i++) {
			for(int j=0;j<n;j++)a[i][j]=sc.nextInt();
		}
		for(int i=0;i<n;i++) {
			int buff=0;
			for(int j=0;j<=i;j++) {
				buff+=a[0][j];
			}
			for(int j=i;j<n;j++) {
				buff+=a[1][j];
			}
			max=Math.max(max, buff);
		}
		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