import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author rizhiy
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[][] a = new int[2][n];
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            }
            a[1][0] += a[0][0];
            for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            }
            for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            }
            out.println(a[1][n - 1]);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.StringTokenizer; StringTokenizer java.util import java.io.IOException; IOException java.io import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.InputStream; InputStream java.io public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[][] a = new int[2][n];
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            }
            a[1][0] += a[0][0];
            for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            }
            for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            }
            out.println(a[1][n - 1]);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out InputReader in = new InputReader(inputStream); in new InputReader(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) TaskA solver = new TaskA(); solver new TaskA() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class TaskA {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[][] a = new int[2][n];
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            }
            a[1][0] += a[0][0];
            for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            }
            for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            }
            out.println(a[1][n - 1]);
        }

    } TaskA public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[][] a = new int[2][n];
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            }
            a[1][0] += a[0][0];
            for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            }
            for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            }
            out.println(a[1][n - 1]);
        } solve {
            int n = in.nextInt();
            int[][] a = new int[2][n];
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            }
            a[1][0] += a[0][0];
            for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            }
            for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            }
            out.println(a[1][n - 1]);
        } int n = in.nextInt(); n in.nextInt() in.nextInt in 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] = in.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] = in.nextInt();
                }
            } {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            } for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
                    a[i][j] = in.nextInt();
                } {
                    a[i][j] = in.nextInt();
                } a[i][j] = in.nextInt() a[i][j] a[i] a i j in.nextInt() in.nextInt in a[1][0] += a[0][0] a[1][0] a[1] a 1 0 a[0][0] a[0] a 0 0 for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            } int i = 1; int i = 1; i 1 i < n i n i++ i++ i {
                a[0][i] += a[0][i - 1];
            } {
                a[0][i] += a[0][i - 1];
            } a[0][i] += a[0][i - 1] a[0][i] a[0] a 0 i a[0][i - 1] a[0] a 0 i - 1 i 1 for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            } int i = 1; int i = 1; i 1 i < 2 i 2 i++ i++ i {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            } {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            } for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                } int j = 1; int j = 1; j 1 j < n j n j++ j++ j {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                } {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                } a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]) a[i][j] a[i] a i j Math.max(a[i - 1][j], a[i][j - 1]) Math.max Math a[i - 1][j] a[i - 1] a i - 1 i 1 j a[i][j - 1] a[i] a i j - 1 j 1 out.println(a[1][n - 1]) out.println out a[1][n - 1] a[1] a 1 n - 1 n 1 int testNumber testNumber InputReader in in PrintWriter out out static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    } InputReader public BufferedReader reader; reader public StringTokenizer tokenizer; tokenizer public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } InputReader {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } reader = new BufferedReader(new InputStreamReader(stream), 32768) reader new BufferedReader(new InputStreamReader(stream), 32768) tokenizer = null tokenizer null InputStream stream stream public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } next {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    tokenizer = new StringTokenizer(reader.readLine());
                } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[][] a = new int[2][n];
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            }
            a[1][0] += a[0][0];
            for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            }
            for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            }
            out.println(a[1][n - 1]);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[][] a = new int[2][n];
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            }
            a[1][0] += a[0][0];
            for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            }
            for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            }
            out.println(a[1][n - 1]);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author rizhiy
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[][] a = new int[2][n];
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < n; j++) {
                    a[i][j] = in.nextInt();
                }
            }
            a[1][0] += a[0][0];
            for (int i = 1; i < n; i++) {
                a[0][i] += a[0][i - 1];
            }
            for (int i = 1; i < 2; i++) {
                for (int j = 1; j < n; j++) {
                    a[i][j] += Math.max(a[i - 1][j], a[i][j - 1]);
                }
            }
            out.println(a[1][n - 1]);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}

