import java.util.Scanner;

class Main {

	public static void main(String args[]){

		Scanner scan = new Scanner(System.in);
		int n;
		n = scan.nextInt();
		int x[][] = new int[2][n];
		
		for(int i = 0; i < 2; i++)
			for(int j = 0; j < n; j++)
				x[i][j] = scan.nextInt();
		
		scan.close();
		
		int sum;
		int max = 0;
		

		for(int i = 0; i < n; i++){
			sum = 0;
			for(int j = 0; j <= i; j++){
				sum += x[0][j];
			}
			for(int j = i; j < n; j++){
				sum += x[1][j];
			}
			if(sum >= max)max =sum;
		}	
		System.out.print(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