#include <iostream>
using namespace std;

int main() {
    char ch1 = 'A';
    char ch2 = 'Z';
    cout << ch1 << ' ' << ch2 << '\n';
    cout << (int)ch1 << ' ' << (int)ch2 << '\n';
    cout << ch2 - ch1 << '\n';
    char x = '9';
    int y = x - '0';
    cout << y << '\n';

    string s = "yes";
    cout << s[0] << ' ' << s[1] << ' ' << s[2] << '\n';
    s[1] = 'o';
    cout << s << '\n';

    for (int i = 0; i < s.length(); ++i) {
        s[i] = 'a';
    }
    cout << s << '\n';

    string t;
    cout << t << '\n';

    string s1 = "ab";
    string s2 = "cd";
    cout << s1 + s2 << '\n'; // Конкатенация строк.
    s1 += s2;
    cout << s1 << '\n'; // abcd
    cout << s1.substr(2, 2) << '\n';
}