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[][] dp = new int[2][n];
		dp[0][0] = a[0][0];
		dp[1][0] = dp[0][0] + a[1][0];
		for(int i = 1 ; i < n ; i++) dp[0][i] = dp[0][i - 1] + a[0][i];
		for(int i = 1 ; i < n ; i++) {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		}
		System.out.println(dp[1][n - 1]);
	}
} 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[][] dp = new int[2][n];
		dp[0][0] = a[0][0];
		dp[1][0] = dp[0][0] + a[1][0];
		for(int i = 1 ; i < n ; i++) dp[0][i] = dp[0][i - 1] + a[0][i];
		for(int i = 1 ; i < n ; i++) {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		}
		System.out.println(dp[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 < 2 ; i++) {
			for(int j = 0 ; j < n ; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int[][] dp = new int[2][n];
		dp[0][0] = a[0][0];
		dp[1][0] = dp[0][0] + a[1][0];
		for(int i = 1 ; i < n ; i++) dp[0][i] = dp[0][i - 1] + a[0][i];
		for(int i = 1 ; i < n ; i++) {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		}
		System.out.println(dp[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 < 2 ; i++) {
			for(int j = 0 ; j < n ; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int[][] dp = new int[2][n];
		dp[0][0] = a[0][0];
		dp[1][0] = dp[0][0] + a[1][0];
		for(int i = 1 ; i < n ; i++) dp[0][i] = dp[0][i - 1] + a[0][i];
		for(int i = 1 ; i < n ; i++) {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		}
		System.out.println(dp[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 < 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[][] dp = new int[2][n]; dp new int[2][n] 2 n dp[0][0] = a[0][0] dp[0][0] dp[0] dp 0 0 a[0][0] a[0] a 0 0 dp[1][0] = dp[0][0] + a[1][0] dp[1][0] dp[1] dp 1 0 dp[0][0] + a[1][0] dp[0][0] dp[0] dp 0 0 a[1][0] a[1] a 1 0 for(int i = 1 ; i < n ; i++) dp[0][i] = dp[0][i - 1] + a[0][i]; int i = 1 ; int i = 1 ; i 1 i < n i n i++ i++ i dp[0][i] = dp[0][i - 1] + a[0][i]; dp[0][i] = dp[0][i - 1] + a[0][i] dp[0][i] dp[0] dp 0 i dp[0][i - 1] + a[0][i] dp[0][i - 1] dp[0] dp 0 i - 1 i 1 a[0][i] a[0] a 0 i for(int i = 1 ; i < n ; i++) {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		} int i = 1 ; int i = 1 ; i 1 i < n i n i++ i++ i {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		} {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		} dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]) dp[1][i] dp[1] dp 1 i Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]) Math.max Math dp[1][i - 1] + a[1][i] dp[1][i - 1] dp[1] dp 1 i - 1 i 1 a[1][i] a[1] a 1 i dp[0][i] + a[1][i] dp[0][i] dp[0] dp 0 i a[1][i] a[1] a 1 i System.out.println(dp[1][n - 1]) System.out.println System.out System System.out dp[1][n - 1] dp[1] dp 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 < 2 ; i++) {
			for(int j = 0 ; j < n ; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int[][] dp = new int[2][n];
		dp[0][0] = a[0][0];
		dp[1][0] = dp[0][0] + a[1][0];
		for(int i = 1 ; i < n ; i++) dp[0][i] = dp[0][i - 1] + a[0][i];
		for(int i = 1 ; i < n ; i++) {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		}
		System.out.println(dp[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 < 2 ; i++) {
			for(int j = 0 ; j < n ; j++) {
				a[i][j] = sc.nextInt();
			}
		}
		int[][] dp = new int[2][n];
		dp[0][0] = a[0][0];
		dp[1][0] = dp[0][0] + a[1][0];
		for(int i = 1 ; i < n ; i++) dp[0][i] = dp[0][i - 1] + a[0][i];
		for(int i = 1 ; i < n ; i++) {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		}
		System.out.println(dp[1][n - 1]);
	}
} 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[][] dp = new int[2][n];
		dp[0][0] = a[0][0];
		dp[1][0] = dp[0][0] + a[1][0];
		for(int i = 1 ; i < n ; i++) dp[0][i] = dp[0][i - 1] + a[0][i];
		for(int i = 1 ; i < n ; i++) {
			dp[1][i] = Math.max(dp[1][i - 1] + a[1][i], dp[0][i] + a[1][i]);
		}
		System.out.println(dp[1][n - 1]);
	}
}
