import java.util.*;

public class Main{
  public static void main(String[]args){
    Scanner sc = new Scanner(System.in);
    int N = Integer.parseInt(sc.nextLine());
    String[] s1 = sc.nextLine().split(" ");
    String[] s2 = sc.nextLine().split(" ");
    int[][] m = new int[2][N];
    for(int i = 0; i < N; i++){
      m[0][i] = Integer.parseInt(s1[i]);
      m[1][i] = Integer.parseInt(s2[i]);
    }
    
    int max = 0;
    for(int i = 0; i < N; i++){
      int n = 0;
      int s = 0;
      for(int j = 0; j < N; j++){
        n += m[s][j];
        if(j == i){
          s++;
          n += m[s][j];
        }
      }
      if(n > max){
        max = n;
      }
    }
    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