func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, k;   string s;   int sol(string a) {     int co = 0;     for (int i = 0; i < k; i++)       if (s[i] != a[i % 3]) co++;     int ans = co;     for (int i = 1; i <= n - k; i++) {       if (s[i - 1] != a[(i - 1) % 3]) co--;       if (s[i + k - 1] != a[(i + k - 1) % 3]) co++;       ans = min(ans, co);     }     return ans;   }   int main() {     int t;     cin >> t;     while (t--) {       cin >> n >> k >> s;       cout << min(min(sol( RGB ), sol( GBR )), sol( BRG )) << endl;     }   }   