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+1][N+1];
    for (int i = 1; i <= 2; i++) {
      for (int j = 1; j <= N; j++) {
        int a = sc.nextInt();
        A[i][j] = a + Math.max(A[i-1][j], A[i][j-1]);
      }
    }
    
    System.out.println(A[2][N]);
  }
}
/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