my code:


#include <string>
#include <iostream>
using namespace std;
int main()
{
    string line;

    getline(cin, line);

    static bool sing = false;
    for(int i = 0; i < line.length(); i++)
    {
        if(sing)
        {
            if((line[i] >= 'A') && (line[i] <= 'Z'))
            {
                char temp = line[i] - ('A'-'a');
                cout << temp;
            }
            else if((line[i] == '.') || (line[i] == '!') || (line[i] == '?'))
            {
                cout << line[i];
                sing = false;
            }
            else if(line[i] == 10 || line[i] == 26)
            {
                cout << '\n';
            }
            else
            {
                cout << line[i];
            }
        }
        else
        {
            if(line[i] >= 'A' && line[i] <= 'Z')
            {
                cout << line[i];
                sing = true;
            }
            else if(line[i] == 10 || line[i] == 26)
            {
                cout << '\n';
            }
            else if((line[i] == '.') || (line[i] == '!') || (line[i] == '?'))
            {
                cout << line[i];
            }
            else
            {
                cout << line[i];
            }
        }
    }
    return 0;
}