#include <bits/stdc++.h>

using namespace std;
                       
const int N = 100010;  

typedef long long ll;   

int n, k;
string s;
ll ans, sum;

void solve()
{
	cin >> n >> k >> s;
	ans = 0;
	sum = 0;
	for (int i = 0; i < k; i++)
		sum += (ll)(s[i] != s[i + 1]);
	for (int i = 0; i < (n - k); i++)
	{
		ans += sum;
		if (i + k + 1 == n) continue;
		sum -= (ll)(s[i] != s[i + 1]);
		sum += (ll)(s[i + k] != s[i + k + 1]);
	}
	cout << ans << "\n";	
}

int main() 
{
	cin.sync_with_stdio(0);
	int T;
	cin >> T;
	for (int i = 0; i < T; i++)
		solve();
	return 0;
}