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];
    int ans = 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 tmp = 0;
      for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      }
      for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      }
      ans = Math.max(tmp, ans);
    }

    System.out.println(ans);

  }
} 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];
    int ans = 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 tmp = 0;
      for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      }
      for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      }
      ans = Math.max(tmp, ans);
    }

    System.out.println(ans);

  }
} Main public static void main(String[] args) {

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

    System.out.println(ans);

  } main {

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

    System.out.println(ans);

  } 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 ans = 0; ans 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 tmp = 0;
      for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      }
      for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      }
      ans = Math.max(tmp, ans);
    } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      int tmp = 0;
      for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      }
      for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      }
      ans = Math.max(tmp, ans);
    } {
      int tmp = 0;
      for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      }
      for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      }
      ans = Math.max(tmp, ans);
    } int tmp = 0; tmp 0 for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      } int j = 0; int j = 0; j 0 j < (n - i) j (n - i) n i j++ j++ j {
        tmp += a[0][j];
      } {
        tmp += a[0][j];
      } tmp += a[0][j] tmp a[0][j] a[0] a 0 j for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      } int j = n - i - 1; int j = n - i - 1; j n - i - 1 n - i - 1 n i 1 j < n j n j++ j++ j {
        tmp += a[1][j];
      } {
        tmp += a[1][j];
      } tmp += a[1][j] tmp a[1][j] a[1] a 1 j ans = Math.max(tmp, ans) ans Math.max(tmp, ans) Math.max Math tmp ans System.out.println(ans) System.out.println System.out System System.out ans 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 ans = 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 tmp = 0;
      for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      }
      for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      }
      ans = Math.max(tmp, ans);
    }

    System.out.println(ans);

  }
} 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 ans = 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 tmp = 0;
      for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      }
      for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      }
      ans = Math.max(tmp, ans);
    }

    System.out.println(ans);

  }
} 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];
    int ans = 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 tmp = 0;
      for (int j = 0; j < (n - i); j++) {
        tmp += a[0][j];
      }
      for (int j = n - i - 1; j < n; j++) {
        tmp += a[1][j];
      }
      ans = Math.max(tmp, ans);
    }

    System.out.println(ans);

  }
}