import java.util.*;

public 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 < 2;i++){
      for(int j = 0;j < n;j++){
        a[i][j] = sc.nextInt();
      }
    }
    int max = 0;
    int x = 0;
    int count = n;
    while(count > 0){
      int sum = 0;
      int i = 0;
      for(int j = 0;j < n;j++){
        sum += a[i][j];
        if(j == x){
          i++;
          sum += a[i][j];
        }
      }
      if(max < sum){
        max = sum;
      }
      x++;
      count--;
    }
    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