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[] sum = new int[N];
		for (int i = 0; i < N; i++) {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		}
		int ans = sum[0];
		for (int i = 0; i < N; i++) {
			if (ans < sum[i])
				ans = sum[i];
		}
		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[] sum = new int[N];
		for (int i = 0; i < N; i++) {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		}
		int ans = sum[0];
		for (int i = 0; i < N; i++) {
			if (ans < sum[i])
				ans = sum[i];
		}
		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[] sum = new int[N];
		for (int i = 0; i < N; i++) {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		}
		int ans = sum[0];
		for (int i = 0; i < N; i++) {
			if (ans < sum[i])
				ans = sum[i];
		}
		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[] sum = new int[N];
		for (int i = 0; i < N; i++) {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		}
		int ans = sum[0];
		for (int i = 0; i < N; i++) {
			if (ans < sum[i])
				ans = sum[i];
		}
		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[] sum = new int[N]; sum new int[N] N for (int i = 0; i < N; i++) {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		} int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		} {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		} int k = 0; k 0 for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			} int j = 0; int j = 0; j 0 j < N j N j++ j++ j {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			} {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			} sum[i] += A[k][j] sum[i] sum i A[k][j] A[k] A k j if (j == i) {
					k++;
					sum[i] += A[k][j];
				} j == i j i {
					k++;
					sum[i] += A[k][j];
				} k++ k sum[i] += A[k][j] sum[i] sum i A[k][j] A[k] A k j int ans = sum[0]; ans sum[0] sum 0 for (int i = 0; i < N; i++) {
			if (ans < sum[i])
				ans = sum[i];
		} int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
			if (ans < sum[i])
				ans = sum[i];
		} {
			if (ans < sum[i])
				ans = sum[i];
		} if (ans < sum[i])
				ans = sum[i]; ans < sum[i] ans sum[i] sum i ans = sum[i] ans sum[i] sum i 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[] sum = new int[N];
		for (int i = 0; i < N; i++) {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		}
		int ans = sum[0];
		for (int i = 0; i < N; i++) {
			if (ans < sum[i])
				ans = sum[i];
		}
		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[] sum = new int[N];
		for (int i = 0; i < N; i++) {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		}
		int ans = sum[0];
		for (int i = 0; i < N; i++) {
			if (ans < sum[i])
				ans = sum[i];
		}
		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[] sum = new int[N];
		for (int i = 0; i < N; i++) {
			int k = 0;
			for (int j = 0; j < N; j++) {
				sum[i] += A[k][j];
				if (j == i) {
					k++;
					sum[i] += A[k][j];
				}
			}
		}
		int ans = sum[0];
		for (int i = 0; i < N; i++) {
			if (ans < sum[i])
				ans = sum[i];
		}
		System.out.println(ans);
	}

}