abc31c.java

import java.io.IOException;
import java.io.InputStream;
import java.util.*;
 
public class Main {
 
    private static final double EPS = 1e-10;
    public static int a[];
    public static void main(String args[]) {
        FastScanner sc = new FastScanner();
        int n = sc.nextInt();
        a=new int[n];
        for(int i=0;i<n;i++){
            a[i]=sc.nextInt();
        }
        int aokiIndex;
        int maxTKHSScore=-Integer.MAX_VALUE;
        int tmp;
        for(int i=0;i<n;i++){//高橋の選んだ手
            aokiIndex=getAokiIndex(i);
            tmp=calcTKHSScore(i,aokiIndex);
            if(maxTKHSScore<tmp){
                maxTKHSScore=tmp;
            }
        }
        System.out.println(maxTKHSScore);
 
    }
 
    //青木をシミュレートして，青木が選ぶとこを返す
    public static int getAokiIndex(int tkhs){
        int maxIndex=-1;
        int max=-100;
        int tmp;
        for(int i=0;i<a.length;i++){
            if(tkhs==i)continue;
 
            tmp=calcAokiScore(tkhs,i);
            if(max<tmp){
                max=tmp;
                maxIndex=i;
            }
        }
        return maxIndex;
    }
 
    //高橋が得る点数を返す
    public static int calcTKHSScore(int tkhs, int aoki){
        int min=Math.min(tkhs,aoki);
        int max=Math.max(tkhs,aoki);
        boolean flag=true;
        int res=0;
        for(int i=min; i<=max; i++){
            if(flag){
                res+=a[i];
            }
            flag=!flag;
        }
        return res;
    }
 
    //青木が得る点数を返す
    public static int calcAokiScore(int tkhs, int aoki){
        int min=Math.min(tkhs,aoki);
        int max=Math.max(tkhs,aoki);
        boolean flag=false;
        int res=0;
        for(int i=min; i<=max; i++){
            if(flag){
                res+=a[i];
            }
            flag=!flag;
        }
        return res;
    }
}
 
class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
 
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
 
    private int readByte() {
        if (hasNextByte()) return buffer[ptr++];
        else return -1;
    }
 
    private boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }
 
    private void skipUnprintable() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    }
 
    public boolean hasNext() {
        skipUnprintable();
        return hasNextByte();
    }
 
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
 
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
 
    public int nextInt() {
        if (!hasNext()) throw new NoSuchElementException();
        int n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
}