import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.InputMismatchException;
import java.util.Map;
import java.util.Objects;

public class Main {

    static long[][] taro;
    static long[][] jiro;

    public static void main(String[] args) {
        InputReader ir = new InputReader(System.in);

        int N = ir.nextInt();
        int[] a = ir.nextIntArray(N);

        taro = new long[N][N];
        jiro = new long[N][N];

        computeWinner(N, a);

        System.out.println(taro[0][N-1]);
    }

    private static void computeWinner(int N, int[] a) {
        for(int i=0; i<N; i++) {
            taro[i][i] = a[i];
            jiro[i][i] = -a[i];
        }

        for(int i=1; i<N; i++) {
            for(int j=0, k=j+i; k<N; j++, k++) {
                    taro[j][k] = Math.max(a[j] + jiro[j+1][k], a[k] + jiro[j][k-1]);
                    jiro[j][k] = Math.min(-a[j] + taro[j+1][k], -a[k] + taro[j][k-1]);
         
            }
        }
    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[8192];
        private int curChar, snumChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int snext() {
            if (snumChars == -1)
                throw new InputMismatchException();
            if (curChar >= snumChars) {
                curChar = 0;
                try {
                    snumChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (snumChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = snext();
            while (isSpaceChar(c))
                c = snext();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = snext();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = snext();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nextLong() {
            int c = snext();
            while (isSpaceChar(c))
                c = snext();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = snext();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = snext();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

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

        public String readString() {
            int c = snext();
            while (isSpaceChar(c))
                c = snext();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = snext();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }
}


Measured memory_bytes: 176444