#include <bits/stdc++.h>
using namespace std;

const int MAX = 100001;

int n, k;
string s;
int diff[MAX];

int main() {
  ios_base::sync_with_stdio(false);
  int t;
  cin >> t;
  while(t--) {
    cin >> n >> k >> s;
    assert(s.length() == n);
    for(int i = 1; i < n; ++i) {
      if (s[i] != s[i-1]) {
        diff[i] = diff[i-1] + 1;
      }
      else {
        diff[i] = diff[i-1];
      }
    }
    int nk = n - k + 1;
    long long ans = 0;
    for(int i = 0; i < k; ++i) {
      ans += diff[i + nk - 1] - diff[i];
    }
    cout << ans << "\n";
  }
  return 0;
}