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