import 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];
        int max = 0;
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < N; j++) {
                A[i][j] = sc.nextInt();
            }
        }
        for (int i = 0; i < N; i++) {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        }
        System.out.println(max);
    }

} import java.util.*; util.* java 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];
        int max = 0;
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < N; j++) {
                A[i][j] = sc.nextInt();
            }
        }
        for (int i = 0; i < N; i++) {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        }
        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];
        int max = 0;
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < N; j++) {
                A[i][j] = sc.nextInt();
            }
        }
        for (int i = 0; i < N; i++) {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        }
        System.out.println(max);
    } main {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[][] A = new int[2][N];
        int max = 0;
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < N; j++) {
                A[i][j] = sc.nextInt();
            }
        }
        for (int i = 0; i < N; i++) {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        }
        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 int max = 0; max 0 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 for (int i = 0; i < N; i++) {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        } {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        } int count = 0; count 0 for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            } int j = 0; int j = 0; j 0 j < N j N j++ j++ j {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            } {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            } if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                } j < i j i {
                    count += A[0][j];
                } count += A[0][j] count A[0][j] A[0] A 0 j if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                } j == i j i {
                    count += A[0][j];
                    count += A[1][j];
                } count += A[0][j] count A[0][j] A[0] A 0 j count += A[1][j] count A[1][j] A[1] A 1 j {
                    count += A[1][j];
                } count += A[1][j] count A[1][j] A[1] A 1 j max = Math.max(max, count) max Math.max(max, count) Math.max Math max count 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];
        int max = 0;
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < N; j++) {
                A[i][j] = sc.nextInt();
            }
        }
        for (int i = 0; i < N; i++) {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        }
        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];
        int max = 0;
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < N; j++) {
                A[i][j] = sc.nextInt();
            }
        }
        for (int i = 0; i < N; i++) {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        }
        System.out.println(max);
    }

} Main
import 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];
        int max = 0;
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < N; j++) {
                A[i][j] = sc.nextInt();
            }
        }
        for (int i = 0; i < N; i++) {
            int count = 0;
            for (int j = 0; j < N; j++) {
                if (j < i) {
                    count += A[0][j];
                } else if (j == i) {
                    count += A[0][j];
                    count += A[1][j];
                } else {
                    count += A[1][j];
                }
            }
            max = Math.max(max, count);
        }
        System.out.println(max);
    }

}
