#include <bits/stdc++.h>
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << " : " << arg1 << "\n";
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " , ";
  __f(comma + 1, args...);
}
int Set(int mask, int pos) { return mask | (1 << pos); }
int Reset(int mask, int pos) { return mask & ~(1 << pos); }
bool Check(int mask, int pos) { return (bool)(mask & (1 << pos)); }
inline long long int gcd(long long int a, long long int b) {
  a = abs(a), b = abs(b);
  while (b) a = a % b, swap(a, b);
  return a;
}
inline long long int power(long long int a, long long int p) {
  long long int res = 1, x = a;
  while (p) {
    if (p & 1) res = (res * x);
    x = (x * x), p >>= 1;
  }
  return res;
}
inline long long int mul_mod(long long int a, long long int p,
                             long long int m) {
  long long int res = 0, x = a % m;
  while (p) {
    if (p & 1) res = (res + x) % m;
    x = (x << 1) % m, p >>= 1;
  }
  return res;
}
inline long long int big_mod(long long int a, long long int p,
                             long long int m) {
  long long int res = 1 % m, x = a % m;
  while (p) {
    if (p & 1) res = (res * x) % m;
    x = (x * x) % m, p >>= 1;
  }
  return res;
}
long long int ext_gcd(long long int A, long long int B, long long int* X,
                      long long int* Y) {
  long long int x2, y2, x1, y1, x, y, r2, r1, q, r;
  x2 = 1, y2 = 0;
  x1 = 0, y1 = 1;
  for (r2 = A, r1 = B; r1 != 0;
       r2 = r1, r1 = r, x2 = x1, y2 = y1, x1 = x, y1 = y) {
    q = r2 / r1, r = r2 % r1;
    x = x2 - (q * x1), y = y2 - (q * y1);
  }
  *X = x2;
  *Y = y2;
  return r2;
}
inline long long int mod_inv(long long int a, long long int m) {
  long long int x, y;
  ext_gcd(a, m, &x, &y);
  x %= m;
  if (x < 0) x += m;
  return x;
}
const int INF = 1e9;
const int nax = 2005;
int n, k;
int main() {
  int q;
  cin >> q;
  while (q--) {
    cin >> n >> k;
    string s;
    cin >> s;
    int ans = INF;
    for (int i = 0; i <= n - k; i++) {
      int x = 0;
      int dir = 0;
      for (int j = i, l = 0; l < k && j < n; j++, l++) {
        if (dir == 0) {
          if (s[j] != 'R') {
            x++;
          }
        } else if (dir == 1) {
          if (s[j] != 'G') {
            x++;
          }
        } else if (dir == 2) {
          if (s[j] != 'B') {
            x++;
          }
        }
        dir = (dir + 1) % 3;
      }
      ans = min(ans, x);
      x = 0;
      dir = 1;
      for (int j = i, l = 0; l < k && j < n; j++, l++) {
        if (dir == 0) {
          if (s[j] != 'G') {
            x++;
          }
        } else if (dir == 1) {
          if (s[j] != 'B') {
            x++;
          }
        } else if (dir == 2) {
          if (s[j] != 'R') {
            x++;
          }
        }
        dir = (dir + 1) % 3;
      }
      ans = min(ans, x);
      x = 0;
      dir = 2;
      for (int j = i, l = 0; l < k && j < n; j++, l++) {
        if (dir == 0) {
          if (s[j] != 'B') {
            x++;
          }
        } else if (dir == 1) {
          if (s[j] != 'R') {
            x++;
          }
        } else if (dir == 2) {
          if (s[j] != 'G') {
            x++;
          }
        }
        dir = (dir + 1) % 3;
      }
      ans = min(ans, x);
    }
    cout << ans << endl;
  }
  return 0;
}
