#include <unistd.h>

int main(int argc, char* argv[])
{
    unsigned char ch;
    if (argc > 1) {
        const char* error = 
            "This program does not accept arguments; use it as a filter.\n\n";
        write(2, error, strlen(error));
        return 1;
    }
    
    while (read(0, &ch, 1) == 1) {
        if (ch == '\n') {
            unsigned char cr = '\r';
            write(1, &cr, 1);
        }
        write(1, &ch, 1);
    }

    return 0;
}