import java.util.*;

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 * N ; i ++){
			if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			}
//			System.out.printf(" A[ %d ][ %d ] = %d \n" , (i < N) ? 0:1 ,(i < N) ? i: i - N,
//			(i < N) ? A[0][i] : A[1][i - N]  );
		}
		
		int maxCandies = 0;
		
		
		for(int i = 0 ; i < N ; i++){
			int sum_i = 0;
			for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			}
			if(maxCandies < sum_i){
				maxCandies = sum_i;
			}
		}
		
		System.out.println(maxCandies);
	}
} import java.util.*; util.* java 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 * N ; i ++){
			if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			}
//			System.out.printf(" A[ %d ][ %d ] = %d \n" , (i < N) ? 0:1 ,(i < N) ? i: i - N,
//			(i < N) ? A[0][i] : A[1][i - N]  );
		}
		
		int maxCandies = 0;
		
		
		for(int i = 0 ; i < N ; i++){
			int sum_i = 0;
			for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			}
			if(maxCandies < sum_i){
				maxCandies = sum_i;
			}
		}
		
		System.out.println(maxCandies);
	}
} 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 * N ; i ++){
			if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			}
//			System.out.printf(" A[ %d ][ %d ] = %d \n" , (i < N) ? 0:1 ,(i < N) ? i: i - N,
//			(i < N) ? A[0][i] : A[1][i - N]  );
		}
		
		int maxCandies = 0;
		
		
		for(int i = 0 ; i < N ; i++){
			int sum_i = 0;
			for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			}
			if(maxCandies < sum_i){
				maxCandies = sum_i;
			}
		}
		
		System.out.println(maxCandies);
	} main {
		Scanner sc = new Scanner(System.in);
		
		int N = sc.nextInt();
		
		int[][] A = new int[2][N];
		
		for(int i = 0 ; i < 2 * N ; i ++){
			if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			}
//			System.out.printf(" A[ %d ][ %d ] = %d \n" , (i < N) ? 0:1 ,(i < N) ? i: i - N,
//			(i < N) ? A[0][i] : A[1][i - N]  );
		}
		
		int maxCandies = 0;
		
		
		for(int i = 0 ; i < N ; i++){
			int sum_i = 0;
			for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			}
			if(maxCandies < sum_i){
				maxCandies = sum_i;
			}
		}
		
		System.out.println(maxCandies);
	} 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 * N ; i ++){
			if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			}
//			System.out.printf(" A[ %d ][ %d ] = %d \n" , (i < N) ? 0:1 ,(i < N) ? i: i - N,
//			(i < N) ? A[0][i] : A[1][i - N]  );
		} int i = 0 ; int i = 0 ; i 0 i < 2 * N i 2 * N 2 N i ++ i ++ i {
			if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			}
//			System.out.printf(" A[ %d ][ %d ] = %d \n" , (i < N) ? 0:1 ,(i < N) ? i: i - N,
//			(i < N) ? A[0][i] : A[1][i - N]  );
		} {
			if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			}
//			System.out.printf(" A[ %d ][ %d ] = %d \n" , (i < N) ? 0:1 ,(i < N) ? i: i - N,
//			(i < N) ? A[0][i] : A[1][i - N]  );
		} if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			} i < N i N {
				A[0][i] = sc.nextInt();
			} A[0][i] = sc.nextInt() A[0][i] A[0] A 0 i sc.nextInt() sc.nextInt sc {
				A[1][i - N] = sc.nextInt();
			} A[1][i - N] = sc.nextInt() A[1][i - N] A[1] A 1 i - N i N sc.nextInt() sc.nextInt sc int maxCandies = 0; maxCandies 0 for(int i = 0 ; i < N ; i++){
			int sum_i = 0;
			for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			}
			if(maxCandies < sum_i){
				maxCandies = sum_i;
			}
		} int i = 0 ; int i = 0 ; i 0 i < N i N i++ i++ i {
			int sum_i = 0;
			for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			}
			if(maxCandies < sum_i){
				maxCandies = sum_i;
			}
		} {
			int sum_i = 0;
			for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			}
			if(maxCandies < sum_i){
				maxCandies = sum_i;
			}
		} int sum_i = 0; sum_i 0 for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			} int j = 0 ; int j = 0 ; j 0 j < N j N j++ j++ j {
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			} {
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			} if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				} j < i j i {
					sum_i = sum_i + A[0][j];
				} sum_i = sum_i + A[0][j] sum_i sum_i + A[0][j] sum_i A[0][j] A[0] A 0 j if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				} j == i j i {
					sum_i = sum_i + A[0][j] + A[1][j] ;
				} sum_i = sum_i + A[0][j] + A[1][j] sum_i sum_i + A[0][j] + A[1][j] sum_i + A[0][j] + A[1][j] sum_i A[0][j] A[0] A 0 j A[1][j] A[1] A 1 j {
					sum_i = sum_i + A[1][j];
				} sum_i = sum_i + A[1][j] sum_i sum_i + A[1][j] sum_i A[1][j] A[1] A 1 j if(maxCandies < sum_i){
				maxCandies = sum_i;
			} maxCandies < sum_i maxCandies sum_i {
				maxCandies = sum_i;
			} maxCandies = sum_i maxCandies sum_i System.out.println(maxCandies) System.out.println System.out System System.out maxCandies String[] args args
import java.util.*;

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 * N ; i ++){
			if(i < N){
				A[0][i] = sc.nextInt();
			}else {
				A[1][i - N] = sc.nextInt();
			}
//			System.out.printf(" A[ %d ][ %d ] = %d \n" , (i < N) ? 0:1 ,(i < N) ? i: i - N,
//			(i < N) ? A[0][i] : A[1][i - N]  );
		}
		
		int maxCandies = 0;
		
		
		for(int i = 0 ; i < N ; i++){
			int sum_i = 0;
			for(int j = 0 ; j < N ; j++){
				if(j < i ){
					sum_i = sum_i + A[0][j];
				}else if(j == i){
					sum_i = sum_i + A[0][j] + A[1][j] ;
				}else {
					sum_i = sum_i + A[1][j];
				}
			}
			if(maxCandies < sum_i){
				maxCandies = sum_i;
			}
		}
		
		System.out.println(maxCandies);
	}
}
