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 Ruby (judge verdict: Wrong Answer)

loop do
  cnt = STDIN.gets.chomp
  break if cnt == '0'

  max = 0
  input = Array.new(cnt.to_i) { STDIN.gets.chomp.to_i }
  sp = input.index { |i| i > 0 } || 0
  ep = input.rindex { |i| i > 0 } || (input.length - 1)
  next if input.empty?
  input[sp..ep].inject(0) do |a, e|
    a = 0 if a < 0
    max = a + e if (a + e) > max
    a + e
  end
  puts max
end