func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   ll inf = 1e18;   using vb = vector<bool>;   using vc = vector<char>;   using vd = vector<double>;   using vi = vector<int>;   using vvi = vector<vi>;   using vll = vector<ll>;   using vvll = vector<vll>;   using pi = pair<int, int>;   using pll = pair<ll, ll>;   int a[8] = {-1, -1, -1, 0, 0, 1, 1, 1};   int b[8] = {-1, 0, 1, -1, 1, -1, 0, 1};   ll mod = 998244353;   ll ans = 0;   ll x(string s, char a) {     ll n = s.size();     if (n == 1) {       if (s[0] == a) {         return 0;       } else {         return 1;       }     }     ll d = 0;     ll e = 0;     string q, w;     for (ll i = 0; i < n / 2; i++) {       q += s[i];       if (s[i] == a) {         d++;       }     }     for (ll i = n / 2; i < n; i++) {       w += s[i];       if (s[i] == a) {         e++;       }     }     ll p = n / 2;     ll ans1 = (p - d) + x(w, a + 1);     ll ans2 = (p - e) + x(q, a + 1);     return min(ans1, ans2);   }   signed main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     ll t;     cin >> t;     while (t--) {       ll n;       cin >> n;       string s;       cin >> s;       ll ans = x(s,  a );       cout << ans <<   n ;     }   }   