Problem:
Maximum Sum Sequence

Given a sequence of numbers a1, a2, a3, ..., an, find the maximum sum of a contiguous subsequence of those numbers. Note that, a subsequence of one element is also a contiquous subsequence.

Input

The input consists of multiple datasets. Each data set consists of:

n
a1
a2
.
.
an

You can assume that 1 ≤ n ≤ 5000 and -100000 ≤ ai ≤ 100000.

The input end with a line consisting of a single 0.

Output

For each dataset, print the maximum sum in a line.

Sample Input

7
-5
-1
6
4
9
-6
-7
13
1
2
3
2
-2
-1
1
2
3
2
1
-2
1
3
1000
-200
201
0

Output for the Sample Input

19
14
1001

Solution in C (judge verdict: Wrong Answer)

#include<stdio.h>
main(){
	int i,j,n,a[5000];
	
	int sum = 0,max = 0;
	
	
	while(1){
		
		max = 0;
	
		scanf("%d",&n);
		
		if(n==0) break;
		
		for(i=0;i<n;i++){
			scanf("%d",&a[i]);
		}
		
		for(i = n - 1; (i >= 0)&&(a[i] <= 0); i--);
		
		n = i;
		
		for(i = 0; (i <= n)&&(a[i] <= 0); i++);

		
		for( ;i <= n; i++){
			
			sum = 0;
			
			for(j = i; j <= n; j++) sum += a[j];
			
			if(sum > max) max = sum;
			
			for(j = n; j >= i; j--){
				
				sum -= a[j];
				
				if(sum > max) max = sum;
				
			}
		}

		printf("%d\n",max);
		
		
		sum = 0;
		max = 0;
		
	}

	return 0;
}