import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int [][]a = new int [n][2];
		
		for(int i = 0; i <= 1 ; i++) {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		}
		int ans = 0;
		
		for(int i = 0; i < n ;i++) {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		}
		System.out.println(ans);

	}

} import java.util.Scanner; Scanner 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 [n][2];
		
		for(int i = 0; i <= 1 ; i++) {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		}
		int ans = 0;
		
		for(int i = 0; i < n ;i++) {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		}
		System.out.println(ans);

	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int [][]a = new int [n][2];
		
		for(int i = 0; i <= 1 ; i++) {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		}
		int ans = 0;
		
		for(int i = 0; i < n ;i++) {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		}
		System.out.println(ans);

	} main {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int [][]a = new int [n][2];
		
		for(int i = 0; i <= 1 ; i++) {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		}
		int ans = 0;
		
		for(int i = 0; i < n ;i++) {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		}
		System.out.println(ans);

	} 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 [n][2]; a new int [n][2] n 2 for(int i = 0; i <= 1 ; i++) {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		} int i = 0; int i = 0; i 0 i <= 1 i 1 i++ i++ i {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		} {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		} for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			} int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
				a[j][i] = sc.nextInt();
			} {
				a[j][i] = sc.nextInt();
			} a[j][i] = sc.nextInt() a[j][i] a[j] a j i sc.nextInt() sc.nextInt sc int ans = 0; ans 0 for(int i = 0; i < n ;i++) {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		} {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		} int sum = 0; sum 0 int x = 0; x 0 int y = 0; y 0 for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			} int j = 0; int j = 0; j 0 j <= n j n j++ j++ j {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			} {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			} sum += a[x][y] sum a[x][y] a[x] a x y if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				} x != i || y == 1 x != i x i y == 1 y 1 {
					x = x + 1 ;
				} x = x + 1 x x + 1 x 1 {
					y = 1;
				} y = 1 y 1 ans = Math.max(ans, sum) ans Math.max(ans, sum) Math.max Math ans sum System.out.println(ans) System.out.println System.out System System.out ans 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 [n][2];
		
		for(int i = 0; i <= 1 ; i++) {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		}
		int ans = 0;
		
		for(int i = 0; i < n ;i++) {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		}
		System.out.println(ans);

	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int [][]a = new int [n][2];
		
		for(int i = 0; i <= 1 ; i++) {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		}
		int ans = 0;
		
		for(int i = 0; i < n ;i++) {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		}
		System.out.println(ans);

	}

} Main
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int [][]a = new int [n][2];
		
		for(int i = 0; i <= 1 ; i++) {
			for(int j = 0; j < n ; j++) {
				a[j][i] = sc.nextInt();
			}
		}
		int ans = 0;
		
		for(int i = 0; i < n ;i++) {
			int sum = 0;
			int x = 0;
			int y = 0;
			for(int j = 0; j <= n ; j++) {
				sum += a[x][y];
				
				if(x != i || y == 1) {
					x = x + 1 ;
				}
				else {
					y = 1;
				}
				
			}
			ans = Math.max(ans, sum);

		}
		System.out.println(ans);

	}

}
