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 total = a[1][n-1];
    for(int i = 0;i<n;i++){
      total += a[0][i];
    }
    max = total;
    for(int i = 0;i<n-1;i++){
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    }
    System.out.println(max);
  }
} import java.util.*; util.* java 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 total = a[1][n-1];
    for(int i = 0;i<n;i++){
      total += a[0][i];
    }
    max = total;
    for(int i = 0;i<n-1;i++){
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    }
    System.out.println(max);
  }
} 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 total = a[1][n-1];
    for(int i = 0;i<n;i++){
      total += a[0][i];
    }
    max = total;
    for(int i = 0;i<n-1;i++){
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    }
    System.out.println(max);
  } main {
    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 total = a[1][n-1];
    for(int i = 0;i<n;i++){
      total += a[0][i];
    }
    max = total;
    for(int i = 0;i<n-1;i++){
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    }
    System.out.println(max);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[][] a = new int[2][n]; a new int[2][n] 2 n for(int i = 0;i<2;i++){
      for(int j = 0;j<n;j++){
        a[i][j] = sc.nextInt();
      }
    } int i = 0; int i = 0; i 0 i<2 i 2 i++ i++ i {
      for(int j = 0;j<n;j++){
        a[i][j] = sc.nextInt();
      }
    } {
      for(int j = 0;j<n;j++){
        a[i][j] = sc.nextInt();
      }
    } for(int j = 0;j<n;j++){
        a[i][j] = sc.nextInt();
      } int j = 0; int j = 0; j 0 j<n j n j++ j++ j {
        a[i][j] = sc.nextInt();
      } {
        a[i][j] = sc.nextInt();
      } a[i][j] = sc.nextInt() a[i][j] a[i] a i j sc.nextInt() sc.nextInt sc int max = 0; max 0 int total = a[1][n-1]; total a[1][n-1] a[1] a 1 n-1 n 1 for(int i = 0;i<n;i++){
      total += a[0][i];
    } int i = 0; int i = 0; i 0 i<n i n i++ i++ i {
      total += a[0][i];
    } {
      total += a[0][i];
    } total += a[0][i] total a[0][i] a[0] a 0 i max = total max total for(int i = 0;i<n-1;i++){
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    } int i = 0; int i = 0; i 0 i<n-1 i n-1 n 1 i++ i++ i {
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    } {
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    } total+=a[1][n-1-i-1] total a[1][n-1-i-1] a[1] a 1 n-1-i-1 i n-1-i-1 n 1 i 1 total-=a[0][n-1-i] total a[0][n-1-i] a[0] a 0 n-1-i n-1-i n 1 i max = Math.max(max,total) max Math.max(max,total) Math.max Math max total System.out.println(max) System.out.println System.out System System.out max String[] args args 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 total = a[1][n-1];
    for(int i = 0;i<n;i++){
      total += a[0][i];
    }
    max = total;
    for(int i = 0;i<n-1;i++){
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    }
    System.out.println(max);
  }
} 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 total = a[1][n-1];
    for(int i = 0;i<n;i++){
      total += a[0][i];
    }
    max = total;
    for(int i = 0;i<n-1;i++){
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    }
    System.out.println(max);
  }
} Main
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 total = a[1][n-1];
    for(int i = 0;i<n;i++){
      total += a[0][i];
    }
    max = total;
    for(int i = 0;i<n-1;i++){
      total+=a[1][n-1-i-1];
      total-=a[0][n-1-i];
      max = Math.max(max,total);
    }
    System.out.println(max);
  }
}
