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[] sum1 = new int[n];
        int[] sum2 = new int[n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        }

        int max = 0;
        for (int i = 0; i < n; i++) {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        }

        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[] sum1 = new int[n];
        int[] sum2 = new int[n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        }

        int max = 0;
        for (int i = 0; i < n; i++) {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        }

        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[] sum1 = new int[n];
        int[] sum2 = new int[n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        }

        int max = 0;
        for (int i = 0; i < n; i++) {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        }

        System.out.println(max);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] A = new int[2][n];
        int[] sum1 = new int[n];
        int[] sum2 = new int[n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        }

        int max = 0;
        for (int i = 0; i < n; i++) {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        }

        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[] sum1 = new int[n]; sum1 new int[n] n int[] sum2 = new int[n]; sum2 new int[n] n for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        } 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();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        } {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        } for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            } {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            } A[i][j] = sc.nextInt() A[i][j] A[i] A i j sc.nextInt() sc.nextInt sc if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                } i == 0 i 0 {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                } sum1[j] = A[i][j] sum1[j] sum1 j A[i][j] A[i] A i j if (j > 0) sum1[j] += sum1[j-1]; j > 0 j 0 sum1[j] += sum1[j-1] sum1[j] sum1 j sum1[j-1] sum1 j-1 j 1 if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                } i == 1 i 1 {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                } sum2[j] = A[i][j] sum2[j] sum2 j A[i][j] A[i] A i j if (j > 0) sum2[j] += sum2[j-1]; j > 0 j 0 sum2[j] += sum2[j-1] sum2[j] sum2 j sum2[j-1] sum2 j-1 j 1 int max = 0; max 0 for (int i = 0; i < n; i++) {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        } {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        } int tmp = sum1[i] + sum2[n-1]; tmp sum1[i] + sum2[n-1] sum1[i] sum1 i sum2[n-1] sum2 n-1 n 1 if (i > 0) tmp -= sum2[i-1]; i > 0 i 0 tmp -= sum2[i-1] tmp sum2[i-1] sum2 i-1 i 1 max = Math.max(max , tmp) max Math.max(max , tmp) Math.max Math max tmp 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[] sum1 = new int[n];
        int[] sum2 = new int[n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        }

        int max = 0;
        for (int i = 0; i < n; i++) {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        }

        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[] sum1 = new int[n];
        int[] sum2 = new int[n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        }

        int max = 0;
        for (int i = 0; i < n; i++) {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        }

        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[] sum1 = new int[n];
        int[] sum2 = new int[n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                A[i][j] = sc.nextInt();

                if (i == 0) {
                    sum1[j] = A[i][j];
                    if (j > 0) sum1[j] += sum1[j-1];
                }
                if (i == 1) {
                    sum2[j] = A[i][j];
                    if (j > 0) sum2[j] += sum2[j-1];
                }
            }
        }

        int max = 0;
        for (int i = 0; i < n; i++) {
            int tmp = sum1[i] + sum2[n-1];
            if (i > 0) tmp -= sum2[i-1];
            max = Math.max(max , tmp);
        }

        System.out.println(max);
    }
}
