The description of this problem is very short. Now give you a string(length N), and ask you the max sum of the substring which the length can't small than M.
The first line is one integer T(T≤20) indicates the number of the test cases. Then for every case, the first line is two integer N(1≤N≤1000000) and M(1≤M≤N).
Then one line contains N integer indicate the number. All the number is between -10000 and 10000.
Output one line with an integer.
2 5 1 1 -2 -2 -2 1 5 2 1 -2 -2 -2 1
1 -1