func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string s;     cin >> s;     vector<set<int> > v(26);     for (int i = 0; i < s.size(); i++) v[s[i] -  a ].insert(i);     int q = 0, op = 0;     cin >> q;     while (q--) {       cin >> op;       if (op == 1) {         int pos = 0;         char x;         cin >> pos >> x;         v[s[pos - 1] -  a ].erase(pos - 1);         s[pos - 1] = x;         v[s[pos - 1] -  a ].insert(pos - 1);       } else {         int l = 0, r = 0, ans = 0;         cin >> l >> r;         for (int i = 0; i < 26; i++) {           auto it = v[i].lower_bound(l - 1);           if (it != v[i].end() && *it <= r - 1) ans++;         }         cout << ans << endl;       }     }     return 0;   }   