import java.util.*;

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