func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 2e5 + 5;   int main() {     int t, n;     string a;     cin >> t;     while (t--) {       cin >> n;       cin >> a;       int l = 0, r = n - 1;       while (a[l] == a[r] && l <= r) l++, r--;       if (l > r)         cout <<  0  << endl;       else {         int ans1 = 0;         int l1 = l, r1 = r;         while (a[l1] == a[l] && l1 <= r1) l1++, ans1++;         while (a[l1] == a[r1] && l1 <= r1) {           l1++, r1--;           if (a[l1] != a[r1]) {             while (a[l1] == a[l] && l1 < r1) l1++, ans1++;             while (a[r1] == a[l] && l1 < r1) r1--, ans1++;           }         }         if (l1 <= r1) ans1 = -1;         int ans2 = 0;         int l2 = l, r2 = r;         while (a[r2] == a[r] && l2 <= r2) r2--, ans2++;         while (a[l2] == a[r2] && l2 <= r2) {           l2++, r2--;           if (a[l2] != a[r2]) {             while (a[l2] == a[r] && l2 < r2) l2++, ans2++;             while (a[r2] == a[r] && l2 < r2) r2--, ans2++;           }         }         if (l2 <= r2) ans2 = -1;         if (ans1 == -1)           cout << ans2 << endl;         else if (ans2 == -1)           cout << ans1 << endl;         else           cout << min(ans1, ans2) << endl;       }     }     return 0;   }   