import java.util.*;
import java.lang.*;
import java.io.*;
class Ideone {
Scanner sc
=new Scanner
(System.
in); int n=sc.nextInt();
int arr[]=new int[n];
for(int i=0;i<n;i++){
arr[i]=sc.nextInt();
}
// brute force
// int ans=Integer.MIN_VALUE;
// for(int k=1;k<n;k++){
// int num1=maxSum(0,k-1,arr);
// int num2=maxSum(k,n-1,arr);
// ans=Math.max(ans,num1+num2);
// }
// System.out.print(ans);
// }
// public static int maxSum(int p,int q,int arr[]){
// int maxArray=Integer.MIN_VALUE;
// int sum=0;
// for(int i=p;i<=q;i++){
// sum += arr[i];
// if(sum>maxArray){
// maxArray=sum;
// }
// if(sum<0){
// sum=0;
// }
// }
// return maxArray;
// }
// }
//OPTIMIZE VERSION
int pfMax[]=new int[n];
int sfMax[]=new int[n];
int sum=0;
int prMaxSum=0;
for(int i=0;i<n;i++){
sum += arr[i];
prMaxSum
= Math.
max(prMaxSum, sum
); if(sum < 0) sum = 0;
pfMax[i]=prMaxSum;
}
sum=0;
int sfMaxSum=0;
for(int i=n-1;i>=0;i--){
sum += arr[i];
sfMaxSum
= Math.
max(sfMaxSum, sum
); if(sum < 0) sum = 0;
sfMax[i]=sfMaxSum;
}
int ans=0;
for(int i=1;i<n;i++){
int combined = pfMax[i-1] + sfMax[i];
ans
= Math.
max(ans, combined
); }
}
}
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