#include <fstream>
using namespace std;
int main()
{
    char a;
    ifstream file ("txt.txt");
    ofstream file1 ("txt1.txt");
    file1 << "[b]";
    while (file >> a)
    {
        if (a == ' ')   {file1 << ' ';}
        else if (a != '\n') {file1 << a;}
        else if (a == '\n') {file1 << "[b]" << '\n' << "[b]";}
    }
}