import java.util.Scanner;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Iterator;
import java.util.Collections;
import java.util.Comparator;
import java.util.Random;

class Main{
        public static void main(String args[]){
                Scanner sc = new Scanner(System.in);
                int N = sc.nextInt();
                int[][] A = new int[3][N+2];
                A[1][0] = 0;
                A[2][N+1] = 0;
                for(int j=1; j<=N; j++){
                        A[1][j] = A[1][j-1] + sc.nextInt();
                }

                for(int j=1; j<=N; j++){
                        A[2][j] = sc.nextInt();
                }

                for(int j=N; j>=1; j--){
                        A[2][j] = A[2][j+1] + A[2][j];
                }

                int Max = 0;
                for(int i=1; i<=N; i++){
                        Max = Math.max(A[1][i]+A[2][i],Max);
                }
                System.out.print(Max);
        }
} import java.util.Scanner; Scanner java.util import java.util.ArrayList; ArrayList java.util import java.util.Arrays; Arrays java.util import java.util.List; List java.util import java.util.Iterator; Iterator java.util import java.util.Collections; Collections java.util import java.util.Comparator; Comparator java.util import java.util.Random; Random java.util class Main{
        public static void main(String args[]){
                Scanner sc = new Scanner(System.in);
                int N = sc.nextInt();
                int[][] A = new int[3][N+2];
                A[1][0] = 0;
                A[2][N+1] = 0;
                for(int j=1; j<=N; j++){
                        A[1][j] = A[1][j-1] + sc.nextInt();
                }

                for(int j=1; j<=N; j++){
                        A[2][j] = sc.nextInt();
                }

                for(int j=N; j>=1; j--){
                        A[2][j] = A[2][j+1] + A[2][j];
                }

                int Max = 0;
                for(int i=1; i<=N; i++){
                        Max = Math.max(A[1][i]+A[2][i],Max);
                }
                System.out.print(Max);
        }
} Main public static void main(String args[]){
                Scanner sc = new Scanner(System.in);
                int N = sc.nextInt();
                int[][] A = new int[3][N+2];
                A[1][0] = 0;
                A[2][N+1] = 0;
                for(int j=1; j<=N; j++){
                        A[1][j] = A[1][j-1] + sc.nextInt();
                }

                for(int j=1; j<=N; j++){
                        A[2][j] = sc.nextInt();
                }

                for(int j=N; j>=1; j--){
                        A[2][j] = A[2][j+1] + A[2][j];
                }

                int Max = 0;
                for(int i=1; i<=N; i++){
                        Max = Math.max(A[1][i]+A[2][i],Max);
                }
                System.out.print(Max);
        } main {
                Scanner sc = new Scanner(System.in);
                int N = sc.nextInt();
                int[][] A = new int[3][N+2];
                A[1][0] = 0;
                A[2][N+1] = 0;
                for(int j=1; j<=N; j++){
                        A[1][j] = A[1][j-1] + sc.nextInt();
                }

                for(int j=1; j<=N; j++){
                        A[2][j] = sc.nextInt();
                }

                for(int j=N; j>=1; j--){
                        A[2][j] = A[2][j+1] + A[2][j];
                }

                int Max = 0;
                for(int i=1; i<=N; i++){
                        Max = Math.max(A[1][i]+A[2][i],Max);
                }
                System.out.print(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[3][N+2]; A new int[3][N+2] 3 N+2 N 2 A[1][0] = 0 A[1][0] A[1] A 1 0 0 A[2][N+1] = 0 A[2][N+1] A[2] A 2 N+1 N 1 0 for(int j=1; j<=N; j++){
                        A[1][j] = A[1][j-1] + sc.nextInt();
                } int j=1; int j=1; j 1 j<=N j N j++ j++ j {
                        A[1][j] = A[1][j-1] + sc.nextInt();
                } {
                        A[1][j] = A[1][j-1] + sc.nextInt();
                } A[1][j] = A[1][j-1] + sc.nextInt() A[1][j] A[1] A 1 j A[1][j-1] + sc.nextInt() A[1][j-1] A[1] A 1 j-1 j 1 sc.nextInt() sc.nextInt sc for(int j=1; j<=N; j++){
                        A[2][j] = sc.nextInt();
                } int j=1; int j=1; j 1 j<=N j N j++ j++ j {
                        A[2][j] = sc.nextInt();
                } {
                        A[2][j] = sc.nextInt();
                } A[2][j] = sc.nextInt() A[2][j] A[2] A 2 j sc.nextInt() sc.nextInt sc for(int j=N; j>=1; j--){
                        A[2][j] = A[2][j+1] + A[2][j];
                } int j=N; int j=N; j N j>=1 j 1 j-- j-- j {
                        A[2][j] = A[2][j+1] + A[2][j];
                } {
                        A[2][j] = A[2][j+1] + A[2][j];
                } A[2][j] = A[2][j+1] + A[2][j] A[2][j] A[2] A 2 j A[2][j+1] + A[2][j] A[2][j+1] A[2] A 2 j+1 j 1 A[2][j] A[2] A 2 j int Max = 0; Max 0 for(int i=1; i<=N; i++){
                        Max = Math.max(A[1][i]+A[2][i],Max);
                } int i=1; int i=1; i 1 i<=N i N i++ i++ i {
                        Max = Math.max(A[1][i]+A[2][i],Max);
                } {
                        Max = Math.max(A[1][i]+A[2][i],Max);
                } Max = Math.max(A[1][i]+A[2][i],Max) Max Math.max(A[1][i]+A[2][i],Max) Math.max Math A[1][i]+A[2][i] A[1][i] A[1] A 1 i A[2][i] A[2] A 2 i Max System.out.print(Max) System.out.print System.out System System.out Max String args[] args
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Iterator;
import java.util.Collections;
import java.util.Comparator;
import java.util.Random;

class Main{
        public static void main(String args[]){
                Scanner sc = new Scanner(System.in);
                int N = sc.nextInt();
                int[][] A = new int[3][N+2];
                A[1][0] = 0;
                A[2][N+1] = 0;
                for(int j=1; j<=N; j++){
                        A[1][j] = A[1][j-1] + sc.nextInt();
                }

                for(int j=1; j<=N; j++){
                        A[2][j] = sc.nextInt();
                }

                for(int j=N; j>=1; j--){
                        A[2][j] = A[2][j+1] + A[2][j];
                }

                int Max = 0;
                for(int i=1; i<=N; i++){
                        Max = Math.max(A[1][i]+A[2][i],Max);
                }
                System.out.print(Max);
        }
}
