import java.util.*;
import java.io.*;

public class Main {
	static int mod = (int) 1e9 + 7;
	static int DX[] = { -1, 0, 1, 0 }, DY[] = { 0, -1, 0, 1 };

	public static void main(String[] args) {
		FastScanner fs = new FastScanner(System.in);
		int n = fs.nextInt();
		int a1[] = fs.nextIntArray(n);
		int a2[] = fs.nextIntArray(n);
		
		int ans = 0;
		for(int i=0;i<n;i++) {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	}
}

//高速なScanner
class FastScanner {
	private BufferedReader reader = null;
	private StringTokenizer tokenizer = null;

	public FastScanner(InputStream in) {
		reader = new BufferedReader(new InputStreamReader(in));
		tokenizer = null;
	}

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

	public String nextLine() {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				return reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken("\n");
	}

	public long nextLong() {
		return Long.parseLong(next());
	}

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

	public double nextDouble() {
		return Double.parseDouble(next());
	}

	public int[] nextIntArray(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = nextInt();
		return a;
	}

	public long[] nextLongArray(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nextLong();
		return a;
	}
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
	static int mod = (int) 1e9 + 7;
	static int DX[] = { -1, 0, 1, 0 }, DY[] = { 0, -1, 0, 1 };

	public static void main(String[] args) {
		FastScanner fs = new FastScanner(System.in);
		int n = fs.nextInt();
		int a1[] = fs.nextIntArray(n);
		int a2[] = fs.nextIntArray(n);
		
		int ans = 0;
		for(int i=0;i<n;i++) {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	}
} Main static int mod = (int) 1e9 + 7; mod (int) 1e9 + 7 (int) 1e9 7 static int DX[] = { -1, 0, 1, 0 } DX { -1, 0, 1, 0 } -1 1 0 1 0 DY[] = { 0, -1, 0, 1 }; DY { 0, -1, 0, 1 } 0 -1 1 0 1 public static void main(String[] args) {
		FastScanner fs = new FastScanner(System.in);
		int n = fs.nextInt();
		int a1[] = fs.nextIntArray(n);
		int a2[] = fs.nextIntArray(n);
		
		int ans = 0;
		for(int i=0;i<n;i++) {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	} main {
		FastScanner fs = new FastScanner(System.in);
		int n = fs.nextInt();
		int a1[] = fs.nextIntArray(n);
		int a2[] = fs.nextIntArray(n);
		
		int ans = 0;
		for(int i=0;i<n;i++) {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	} FastScanner fs = new FastScanner(System.in); fs new FastScanner(System.in) int n = fs.nextInt(); n fs.nextInt() fs.nextInt fs int a1[] = fs.nextIntArray(n); a1 fs.nextIntArray(n) fs.nextIntArray fs n int a2[] = fs.nextIntArray(n); a2 fs.nextIntArray(n) fs.nextIntArray fs n int ans = 0; ans 0 for(int i=0;i<n;i++) {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		} int i=0; int i=0; i 0 i<n i n i++ i++ i {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		} {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		} int sum = 0; sum 0 for(int j=0;j<=i;j++) {
				sum += a1[j];
			} int j=0; int j=0; j 0 j<=i j i j++ j++ j {
				sum += a1[j];
			} {
				sum += a1[j];
			} sum += a1[j] sum a1[j] a1 j for(int j=i;j<n;j++) {
				sum += a2[j];
			} int j=i; int j=i; j i j<n j n j++ j++ j {
				sum += a2[j];
			} {
				sum += a2[j];
			} sum += a2[j] sum a2[j] a2 j ans = Math.max(ans, sum) ans Math.max(ans, sum) Math.max Math ans sum System.out.println(ans) System.out.println System.out System System.out ans String[] args args class FastScanner {
	private BufferedReader reader = null;
	private StringTokenizer tokenizer = null;

	public FastScanner(InputStream in) {
		reader = new BufferedReader(new InputStreamReader(in));
		tokenizer = null;
	}

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

	public String nextLine() {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				return reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken("\n");
	}

	public long nextLong() {
		return Long.parseLong(next());
	}

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

	public double nextDouble() {
		return Double.parseDouble(next());
	}

	public int[] nextIntArray(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = nextInt();
		return a;
	}

	public long[] nextLongArray(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nextLong();
		return a;
	}
} FastScanner private BufferedReader reader = null; reader null private StringTokenizer tokenizer = null; tokenizer null public FastScanner(InputStream in) {
		reader = new BufferedReader(new InputStreamReader(in));
		tokenizer = null;
	} FastScanner {
		reader = new BufferedReader(new InputStreamReader(in));
		tokenizer = null;
	} reader = new BufferedReader(new InputStreamReader(in)) reader new BufferedReader(new InputStreamReader(in)) tokenizer = null tokenizer null InputStream in in public String next() {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				tokenizer = new StringTokenizer(reader.readLine());
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken();
	} next {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				tokenizer = new StringTokenizer(reader.readLine());
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken();
	} if (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 String nextLine() {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				return reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken("\n");
	} nextLine {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				return reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken("\n");
	} if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				return 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 {
				return reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		} try {
				return 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) {
				return reader.readLine();
			} return reader.readLine(); reader.readLine() reader.readLine reader return tokenizer.nextToken("\n"); tokenizer.nextToken("\n") tokenizer.nextToken tokenizer "\n" public long nextLong() {
		return Long.parseLong(next());
	} nextLong {
		return Long.parseLong(next());
	} return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next 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 double nextDouble() {
		return Double.parseDouble(next());
	} nextDouble {
		return Double.parseDouble(next());
	} return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public int[] nextIntArray(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = nextInt();
		return a;
	} nextIntArray {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = nextInt();
		return a;
	} int[] a = new int[n]; a new int[n] n for (int i = 0; i < n; i++)
			a[i] = nextInt(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = nextInt(); a[i] = nextInt() a[i] a i nextInt() nextInt return a; a int n n public long[] nextLongArray(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nextLong();
		return a;
	} nextLongArray {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nextLong();
		return a;
	} long[] a = new long[n]; a new long[n] n for (int i = 0; i < n; i++)
			a[i] = nextLong(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = nextLong(); a[i] = nextLong() a[i] a i nextLong() nextLong return a; a int n n public class Main {
	static int mod = (int) 1e9 + 7;
	static int DX[] = { -1, 0, 1, 0 }, DY[] = { 0, -1, 0, 1 };

	public static void main(String[] args) {
		FastScanner fs = new FastScanner(System.in);
		int n = fs.nextInt();
		int a1[] = fs.nextIntArray(n);
		int a2[] = fs.nextIntArray(n);
		
		int ans = 0;
		for(int i=0;i<n;i++) {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	}
} public class Main {
	static int mod = (int) 1e9 + 7;
	static int DX[] = { -1, 0, 1, 0 }, DY[] = { 0, -1, 0, 1 };

	public static void main(String[] args) {
		FastScanner fs = new FastScanner(System.in);
		int n = fs.nextInt();
		int a1[] = fs.nextIntArray(n);
		int a2[] = fs.nextIntArray(n);
		
		int ans = 0;
		for(int i=0;i<n;i++) {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	}
} Main
import java.util.*;
import java.io.*;

public class Main {
	static int mod = (int) 1e9 + 7;
	static int DX[] = { -1, 0, 1, 0 }, DY[] = { 0, -1, 0, 1 };

	public static void main(String[] args) {
		FastScanner fs = new FastScanner(System.in);
		int n = fs.nextInt();
		int a1[] = fs.nextIntArray(n);
		int a2[] = fs.nextIntArray(n);
		
		int ans = 0;
		for(int i=0;i<n;i++) {
			int sum = 0;
			for(int j=0;j<=i;j++) {
				sum += a1[j];
			}
			for(int j=i;j<n;j++) {
				sum += a2[j];
			}
			ans = Math.max(ans, sum);
		}
		System.out.println(ans);
	}
}

//高速なScanner
class FastScanner {
	private BufferedReader reader = null;
	private StringTokenizer tokenizer = null;

	public FastScanner(InputStream in) {
		reader = new BufferedReader(new InputStreamReader(in));
		tokenizer = null;
	}

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

	public String nextLine() {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				return reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken("\n");
	}

	public long nextLong() {
		return Long.parseLong(next());
	}

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

	public double nextDouble() {
		return Double.parseDouble(next());
	}

	public int[] nextIntArray(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = nextInt();
		return a;
	}

	public long[] nextLongArray(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nextLong();
		return a;
	}
}