import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int map[][] = new int[2][N];
        for(int i = 0; i < 2; i++){
            for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            }
        }
        
        int max = 0;
        for(int i = 0; i < N; i++){
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        }
        max += map[0][0] + map[1][N-1];
        
        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 map[][] = new int[2][N];
        for(int i = 0; i < 2; i++){
            for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            }
        }
        
        int max = 0;
        for(int i = 0; i < N; i++){
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        }
        max += map[0][0] + map[1][N-1];
        
        System.out.println(max);
    }
    
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int map[][] = new int[2][N];
        for(int i = 0; i < 2; i++){
            for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            }
        }
        
        int max = 0;
        for(int i = 0; i < N; i++){
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        }
        max += map[0][0] + map[1][N-1];
        
        System.out.println(max);
    } main {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int map[][] = new int[2][N];
        for(int i = 0; i < 2; i++){
            for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            }
        }
        
        int max = 0;
        for(int i = 0; i < N; i++){
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        }
        max += map[0][0] + map[1][N-1];
        
        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 map[][] = new int[2][N]; map new int[2][N] 2 N for(int i = 0; i < 2; i++){
            for(int j = 0; j < N; j++){
                map[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++){
                map[i][j] = sc.nextInt();
            }
        } {
            for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            }
        } for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            } int j = 0; int j = 0; j 0 j < N j N j++ j++ j {
                map[i][j] = sc.nextInt();
            } {
                map[i][j] = sc.nextInt();
            } map[i][j] = sc.nextInt() map[i][j] map[i] map i j sc.nextInt() sc.nextInt sc int max = 0; max 0 for(int i = 0; i < N; i++){
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        } {
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        } int down = 0 down 0 sum = 0; sum 0 for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            } int j = 0; int j = 0; j 0 j < N-1 j N-1 N 1 j++ j++ j {
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            } {
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            } if(i == j)
                    down = 1; i == j i j down = 1 down 1 sum += map[down][j+1-down] sum map[down][j+1-down] map[down] map down j+1-down j+1 j 1 down max = sum > max ? sum : max max sum > max ? sum : max sum > max sum max sum max max += map[0][0] + map[1][N-1] max map[0][0] + map[1][N-1] map[0][0] map[0] map 0 0 map[1][N-1] map[1] map 1 N-1 N 1 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 map[][] = new int[2][N];
        for(int i = 0; i < 2; i++){
            for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            }
        }
        
        int max = 0;
        for(int i = 0; i < N; i++){
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        }
        max += map[0][0] + map[1][N-1];
        
        System.out.println(max);
    }
    
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int map[][] = new int[2][N];
        for(int i = 0; i < 2; i++){
            for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            }
        }
        
        int max = 0;
        for(int i = 0; i < N; i++){
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        }
        max += map[0][0] + map[1][N-1];
        
        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 map[][] = new int[2][N];
        for(int i = 0; i < 2; i++){
            for(int j = 0; j < N; j++){
                map[i][j] = sc.nextInt();
            }
        }
        
        int max = 0;
        for(int i = 0; i < N; i++){
            int down = 0, sum = 0;
            for(int j = 0; j < N-1; j++){
                if(i == j)
                    down = 1;
                sum += map[down][j+1-down];
            }
            max = sum > max ? sum : max;
        }
        max += map[0][0] + map[1][N-1];
        
        System.out.println(max);
    }
    
}