
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 sum2 =0;
		for (int i=0;i<N;i++) {
			sum2+=A[1][i];
		}
		int max=0;
		int sum =0;
		for (int i=0;i<N;i++) {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		}
		System.out.println(max);
	}

} 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 sum2 =0;
		for (int i=0;i<N;i++) {
			sum2+=A[1][i];
		}
		int max=0;
		int sum =0;
		for (int i=0;i<N;i++) {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		}
		System.out.println(max);
	}

} 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 sum2 =0;
		for (int i=0;i<N;i++) {
			sum2+=A[1][i];
		}
		int max=0;
		int sum =0;
		for (int i=0;i<N;i++) {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		}
		System.out.println(max);
	} 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 sum2 =0;
		for (int i=0;i<N;i++) {
			sum2+=A[1][i];
		}
		int max=0;
		int sum =0;
		for (int i=0;i<N;i++) {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		}
		System.out.println(max);
	} 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 sum2 =0; sum2 0 for (int i=0;i<N;i++) {
			sum2+=A[1][i];
		} int i=0; int i=0; i 0 i<N i N i++ i++ i {
			sum2+=A[1][i];
		} {
			sum2+=A[1][i];
		} sum2+=A[1][i] sum2 A[1][i] A[1] A 1 i int max=0; max 0 int sum =0; sum 0 for (int i=0;i<N;i++) {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		} int i=0; int i=0; i 0 i<N i N i++ i++ i {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		} {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		} sum +=A[0][i] sum A[0][i] A[0] A 0 i int temp=sum+sum2; temp sum+sum2 sum sum2 sum2-=A[1][i] sum2 A[1][i] A[1] A 1 i if (max<temp) {
				max = temp;
			} max<temp max temp {
				max = temp;
			} max = temp max temp System.out.println(max) System.out.println System.out System System.out max 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 sum2 =0;
		for (int i=0;i<N;i++) {
			sum2+=A[1][i];
		}
		int max=0;
		int sum =0;
		for (int i=0;i<N;i++) {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		}
		System.out.println(max);
	}

} 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 sum2 =0;
		for (int i=0;i<N;i++) {
			sum2+=A[1][i];
		}
		int max=0;
		int sum =0;
		for (int i=0;i<N;i++) {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		}
		System.out.println(max);
	}

} 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 sum2 =0;
		for (int i=0;i<N;i++) {
			sum2+=A[1][i];
		}
		int max=0;
		int sum =0;
		for (int i=0;i<N;i++) {
			sum +=A[0][i];
			int temp=sum+sum2;
			sum2-=A[1][i];
			if (max<temp) {
				max = temp;
			}
		}
		System.out.println(max);
	}

}