write a go solution for Description:
The cuteness of a binary string is the number of texttt1s divided by the length of the string. For example, the cuteness of texttt01101 is 3/5.

Juju has a binary string s of length n. She wants to choose some non-intersecting subsegments of s such that their concatenation has length m and it has the same cuteness as the string s.

More specifically, she wants to find two arrays l and r of equal length k such that 1<=l_1<=r_1<l_2<=r_2<ldots<l_k<=r_k<=n, and also:

- sumlimits_i=1^k(r_i-l_i+1)=m;
- The cuteness of s[l_1,r_1]+s[l_2,r_2]+ldots+s[l_k,r_k] is equal to the cuteness of s, where s[x,y] denotes the subsegment s_xs_x+1ldotss_y, and + denotes string concatenation.

Juju does not like splitting the string into many parts, so she also wants to minimize the value of k. Find the minimum value of k such that there exist l and r that satisfy the constraints above or determine that it is impossible to find such l and r for any k.

Input Format:
The first line contains a single integer t (1<=t<=10^4) — the number of test cases.

The first line of each test case contains two integers n and m (1<=m<=n<=2*10^5).

The second line of each test case contains a binary string s of length n.

It is guaranteed that the sum of n over all test cases does not exceed 2*10^5.

Output Format:
For each test case, if there is no valid pair of l and r, print -1.

Otherwise, print k+1 lines.

In the first line, print a number k (1<=k<=m) — the minimum number of subsegments required.

Then print k lines, the i-th should contain l_i and r_i (1<=l_i<=r_i<=n) — the range of the i-th subsegment. Note that you should output the subsegments such that the inequality l_1<=qr_1<l_2<=qr_2<ldots<l_k<=qr_k is true.

Note:
In the first example, the cuteness of texttt0011 is the same as the cuteness of texttt01.

In the second example, the cuteness of texttt11000011 is 1/2 and there is no subsegment of size 6 with the same cuteness. So we must use 2 disjoint subsegments texttt10 and texttt0011.

In the third example, there are 8 ways to split the string such that sumlimits_i=1^k(r_i-l_i+1)=3 but none of them has the same cuteness as texttt0101.

In the last example, we don't have to split the string.. Output only the code with no comments, explanation, or additional text.