#include <stdio.h>
#include <stdlib.h>

main(int argc, char *argv[])
{   int c, b=0;
    FILE *fp;
    if (argc == 1) fp = stdin;
    else if ((fp=fopen(argv[1],"r")) == NULL)
        { fprintf(stderr, "file %s not found\n", argv[1]); exit(1); }
    while ((c=getc(fp)) != EOF) {
        if (c == '\n') { if (b != '\r') putchar('\r'); }
        else putchar(c);
        b = c;
    }
    if (fp != stdin) fclose(fp);
}