import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();

		int[][] a = new int[2][n];
		// スペース区切りの整数の入力

		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < n; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		}

		System.out.println(ans);

	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();

		int[][] a = new int[2][n];
		// スペース区切りの整数の入力

		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < n; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		}

		System.out.println(ans);

	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();

		int[][] a = new int[2][n];
		// スペース区切りの整数の入力

		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < n; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		}

		System.out.println(ans);

	} main {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();

		int[][] a = new int[2][n];
		// スペース区切りの整数の入力

		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < n; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		}

		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 int ans = 0; ans 0 for (int i = 0; i < n; i++) {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		} {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		} int max = 0; max 0 for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			} int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			} {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			} if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				} i == j i j {
					max = max + a[1][j] + a[0][j];
				} max = max + a[1][j] + a[0][j] max max + a[1][j] + a[0][j] max + a[1][j] + a[0][j] max a[1][j] a[1] a 1 j a[0][j] a[0] a 0 j if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				} i < j i j {
					max = max + a[1][j];
				} max = max + a[1][j] max max + a[1][j] max a[1][j] a[1] a 1 j {
					max = max + a[0][j];
				} max = max + a[0][j] max max + a[0][j] max a[0][j] a[0] a 0 j if (ans < max) {
				ans = max;
			} ans < max ans max {
				ans = max;
			} ans = max ans max 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);
		// 整数の入力
		int n = sc.nextInt();

		int[][] a = new int[2][n];
		// スペース区切りの整数の入力

		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < n; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		}

		System.out.println(ans);

	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();

		int[][] a = new int[2][n];
		// スペース区切りの整数の入力

		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < n; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		}

		System.out.println(ans);

	}
} Main
import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();

		int[][] a = new int[2][n];
		// スペース区切りの整数の入力

		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < n; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int max = 0;
			for (int j = 0; j < n; j++) {
				if (i == j) {
					max = max + a[1][j] + a[0][j];
				} else if (i < j) {
					max = max + a[1][j];
				} else {
					max = max + a[0][j];
				}
			}
			if (ans < max) {
				ans = max;
			}
		}

		System.out.println(ans);

	}
}
