func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     unordered_map<char, int> check;     int n, count = 0;     cin >> n;     string temp;     cin >> temp;     for (int i = 0; i < temp.size() - 1; i += 2) {       check[temp[i]]++;       char ch = temp[i + 1];       ch = tolower(ch);       if (check.find(ch) != check.end()) {         if (check[ch] == 1)           check.erase(ch);         else           check[ch]--;       } else {         count++;       }     }     cout << count;     return 0;   }   