func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios::sync_with_stdio(0);     string s;     cin >> s;     char x =  a ;     int y;     set<int> arr[26];     for (int i = 0; i < s.length(); i++) {       y = s[i] - x;       arr[y].insert(i);     }     int q;     cin >> q;     int n, ans = 0;     for (int i = 0; i < q; i++) {       cin >> n;       if (n == 1) {         int pos;         char c;         cin >> pos >> c;         y = s[pos - 1] - x;         arr[y].erase(pos - 1);         s[pos - 1] = c;         y = c - x;         arr[y].insert(pos - 1);       }       if (n == 2) {         int l, r;         cin >> l >> r;         l--;         r--;         for (int i = 0; i < 26; i++) {           auto it = arr[i].lower_bound(l);           if (it == arr[i].end())             continue;           else if (*it <= r)             ans++;         }         cout << ans << endl;         ans = 0;       }     }     return 0;   }   