import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		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();
			}
		}
		sc.close();

		int ans = 0;
		for (int i = 0; i < n; i++) {
			int sum = 0;
			for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			}
			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) throws Exception {
		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();
			}
		}
		sc.close();

		int ans = 0;
		for (int i = 0; i < n; i++) {
			int sum = 0;
			for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	}
} Main public static void main(String[] args) throws Exception {
		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();
			}
		}
		sc.close();

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

		int ans = 0;
		for (int i = 0; i < n; i++) {
			int sum = 0;
			for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			}
			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[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();
			}
		} 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] = sc.nextInt() a[i][j] a[i] a i j sc.nextInt() sc.nextInt sc sc.close() sc.close sc int ans = 0; ans 0 for (int i = 0; i < n; i++) {
			int sum = 0;
			for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			}
			ans = Math.max(ans, sum);
		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			int sum = 0;
			for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			}
			ans = Math.max(ans, sum);
		} {
			int sum = 0;
			for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			}
			ans = Math.max(ans, sum);
		} int sum = 0; sum 0 for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			} int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			} {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			} if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				} j < i j i {
					sum += a[0][j];
				} sum += a[0][j] sum a[0][j] a[0] a 0 j if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				} j == i j i {
					sum += a[0][j];
					sum += a[1][j];
				} sum += a[0][j] sum a[0][j] a[0] a 0 j sum += a[1][j] sum a[1][j] a[1] a 1 j {
					sum += a[1][j];
				} sum += a[1][j] sum a[1][j] a[1] a 1 j 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) throws Exception {
		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();
			}
		}
		sc.close();

		int ans = 0;
		for (int i = 0; i < n; i++) {
			int sum = 0;
			for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		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();
			}
		}
		sc.close();

		int ans = 0;
		for (int i = 0; i < n; i++) {
			int sum = 0;
			for (int j = 0; j < n; j++) {
				if (j < i) {
					sum += a[0][j];
				} else if (j == i) {
					sum += a[0][j];
					sum += a[1][j];
				} else {
					sum += a[1][j];
				}
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		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();
			}
		}
		sc.close();

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