CF1898A.Milica and String

传统题 时间 2000 ms 内存 256 MiB 3 尝试 1 已通过 1 标签

Milica and String

Milica has a string ss of length nn, consisting only of characters A and B. She wants to modify ss so it contains exactly kk instances of B. In one operation, she can do the following:

  • Select an integer ii (1in1 \leq i \leq n) and a character cc (cc is equal to either A or B).
  • Then, replace each of the first ii characters of string ss (that is, characters s1,s2,,sis_1, s_2, \ldots, s_i) with cc.

Milica does not want to perform too many operations in order not to waste too much time on them.

She asks you to find the minimum number of operations required to modify ss so it contains exactly kk instances of B. She also wants you to find these operations (that is, integer ii and character cc selected in each operation).

Input

Each test contains multiple test cases. The first line contains the number of test cases tt (1t5001 \leq t \leq 500). The description of test cases follows.

The first line of each test case contains two integers nn and kk (3n1003 \leq n \leq 100, 0kn0 \leq k \leq n) — the length of the string ss and the number of characters B Milica wants to appear in ss in the end.

The second line of each test case contains the string ss of length nn, consisting only of characters A and B.

Output

For each test case, in the first line output a single integer mm — the minimum number of operations Milica should perform.

In the jj-th of the next mm lines output an integer ii (1in1 \le i \le n) and a character cc (cc is 'A' or 'B') — the parameters of the jj-th operation as described in the statement.

If there are multiple solutions with the minimum possible number of operations, output any of them.

Note

In the first test case, there are already 22 characters B in ss, so Milica does not have to perform any operations.

In the second test case, the only way to achieve 33 characters B in ss in one operation is to replace the first character of ss by B on the first operation: AABAB \rightarrow BABAB.

In the third test case, the only way to achieve 00 characters B in ss in one operation is to replace the first 55 characters of ss by A on the first operation: BBBBB \rightarrow AAAAA.

In the fourth test case, one of the ways to achieve 00 characters B in ss in one operation is to replace the first 22 characters of ss by A on the first operation: BAA \rightarrow AAA. Note that "1 A" and "3 A" are also correct one-operation solutions.

Samples

5
5 2
AAABB
5 3
AABAB
5 0
BBBBB
3 0
BAA
10 3
BBBABBBBAB
0
1
1 B
1
5 A
1
2 A
1
6 A

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