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[2][n];
		for (int i = 0; i < 2; i++)
			for (int j = 0; j < n; j++)
				a[i][j] = sc.nextInt();
		int ans = a[0][0];
		for (int k = 0; k < n; k++) {
			ans += a[1][k];
		}
		for (int k = 1; k < n; k++) {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		}
		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[2][n];
		for (int i = 0; i < 2; i++)
			for (int j = 0; j < n; j++)
				a[i][j] = sc.nextInt();
		int ans = a[0][0];
		for (int k = 0; k < n; k++) {
			ans += a[1][k];
		}
		for (int k = 1; k < n; k++) {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		}
		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[2][n];
		for (int i = 0; i < 2; i++)
			for (int j = 0; j < n; j++)
				a[i][j] = sc.nextInt();
		int ans = a[0][0];
		for (int k = 0; k < n; k++) {
			ans += a[1][k];
		}
		for (int k = 1; k < n; k++) {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		}
		System.out.println(ans);
	} 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 ans = a[0][0];
		for (int k = 0; k < n; k++) {
			ans += a[1][k];
		}
		for (int k = 1; k < n; k++) {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		}
		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[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(); 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] a[i] a i j sc.nextInt() sc.nextInt sc int ans = a[0][0]; ans a[0][0] a[0] a 0 0 for (int k = 0; k < n; k++) {
			ans += a[1][k];
		} int k = 0; int k = 0; k 0 k < n k n k++ k++ k {
			ans += a[1][k];
		} {
			ans += a[1][k];
		} ans += a[1][k] ans a[1][k] a[1] a 1 k for (int k = 1; k < n; k++) {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		} int k = 1; int k = 1; k 1 k < n k n k++ k++ k {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		} {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		} int t = 0; t 0 for (int l = 0; l < k; l++)
				t += a[0][l]; int l = 0; int l = 0; l 0 l < k l k l++ l++ l t += a[0][l]; t += a[0][l] t a[0][l] a[0] a 0 l for (int l = k - 1; l < n; l++)
				t += a[1][l]; int l = k - 1; int l = k - 1; l k - 1 k 1 l < n l n l++ l++ l t += a[1][l]; t += a[1][l] t a[1][l] a[1] a 1 l if (t > ans)
				ans = t; t > ans t ans ans = t ans t 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[2][n];
		for (int i = 0; i < 2; i++)
			for (int j = 0; j < n; j++)
				a[i][j] = sc.nextInt();
		int ans = a[0][0];
		for (int k = 0; k < n; k++) {
			ans += a[1][k];
		}
		for (int k = 1; k < n; k++) {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		}
		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[2][n];
		for (int i = 0; i < 2; i++)
			for (int j = 0; j < n; j++)
				a[i][j] = sc.nextInt();
		int ans = a[0][0];
		for (int k = 0; k < n; k++) {
			ans += a[1][k];
		}
		for (int k = 1; k < n; k++) {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		}
		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[2][n];
		for (int i = 0; i < 2; i++)
			for (int j = 0; j < n; j++)
				a[i][j] = sc.nextInt();
		int ans = a[0][0];
		for (int k = 0; k < n; k++) {
			ans += a[1][k];
		}
		for (int k = 1; k < n; k++) {
			int t = 0;
			for (int l = 0; l < k; l++)
				t += a[0][l];
			for (int l = k - 1; l < n; l++)
				t += a[1][l];
			if (t > ans)
				ans = t;
		}
		System.out.println(ans);
	}
}