G. Balanced Distributiontime limit per test2 secondsmemory limit per test512 megabytesinputstandard inputoutputstandard outputThere are n friends living on a circular street. The friends and their houses are numbered clockwise from 0 to n-1.Initially person i has a_i stones. The friends want to make the distribution of stones among them perfectly balanced: everyone should possess the same number of stones.The only way to change the distribution of stones is by conducting meetings. During a meeting, people from exactly k consecutive houses (remember that the street is circular) gather at the same place and bring all their stones with them. All brought stones may be redistributed among people attending the meeting arbitrarily. The total number of stones they possess before the meeting and after the meeting must stay the same. After the meeting, everyone returns to their home.Find a way to make the distribution of stones perfectly balanced conducting as few meetings as possible.InputThe first line contains two integers n and k (2 \le k < n \le 10^5), denoting the number of friends and the size of each meeting.The second line contains n integers a_0, a_1, \ldots, a_{n-1} (0 \le a_i \le 10^4), denoting the number of stones people initially have.The sum of all a_i is divisible by n.OutputOutput the minimum number of meetings m (m \ge 0), followed by m descriptions of meetings in chronological order.The i-th description must consist of an integer s_i (0 \le s_i < n), followed by k non-negative integers b_{i, 0}, b_{i, 1}, \ldots, b_{i, k-1} (b_{i, j} \ge 0). Such a description denotes a meeting of people s_i, (s_i + 1) \bmod n, \ldots, (s_i + k - 1) \bmod n, and b_{i,j} denotes the number of stones person (s_i + j) \bmod n must have after the i-th meeting. The sum of b_{i, j} must match the total number of stones owned by these people before the i-th meeting.We can show that a solution exists for any valid input, and any correct output contains at most 10^7 non-whitespace characters.ExamplesInput
6 3
2 6 1 10 3 2
Output
3
2 7 3 4
5 4 4 2
1 4 4 4
Input
11 4
1 0 1 0 0 4 4 2 4 3 3
Output
3
3 2 2 2 2
8 2 2 2 5
10 2 2 2 2
NoteIn the first example, the distribution of stones changes as follows:   after the first meeting: 2 6 \mathbf{7} \mathbf{3} \mathbf{4} 2;  after the second meeting: \mathbf{4} \mathbf{2} 7 3 4 \mathbf{4};  after the third meeting: 4 \mathbf{4} \mathbf{4} \mathbf{4} 4 4. In the second example, the distribution of stones changes as follows:   after the first meeting: 1 0 1 \mathbf{2} \mathbf{2} \mathbf{2} \mathbf{2} 2 4 3 3;  after the second meeting: \mathbf{5} 0 1 2 2 2 2 2 \mathbf{2} \mathbf{2} \mathbf{2};  after the third meeting: \mathbf{2} \mathbf{2} \mathbf{2} 2 2 2 2 2 2 2 \mathbf{2}. 
6 3
2 6 1 10 3 2

3 2 7 3 4 5 4 4 2 1 4 4 4 
['data structures', 'dp', 'greedy', '*3500']