import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
public class Ztry2 {
static int jia[];
static List<Integer> list=new ArrayList<>();
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
int count=sc.nextInt();
jia=new int[count];
for(int i=0;i<count;i++){
jia[i]=sc.nextInt();
}
if(count==1) System.out.print(jia[0]);
solve(0,count,jia[0],true);
for(int i=1;i<count;i++){
solve(i,count,jia[i],false);
}
Collections.sort(list);
//System.out.print(list);
System.out.print(list.get(list.size()-1));
}
public static void solve(int n,int counter,int price,boolean flag){
for(int i=n+2;i<counter;i++){
if(jia[i]>jia[n]){
int myprice=price+jia[i];
solve(i,counter,myprice,flag);
}
}
if(flag==true&&n==counter-1){
list.add(price-jia[counter-1]);
}
else list.add(price);
}
}