#include <stdio.h>
#include <string.h>
#include <regex.h>

char buf[5001];

main(int argc, char **argv)
{

  char *pattern;
  char eoln;
  regex_t re;

  int firstline=1;

  if(argc < 2)
/*     pattern="[ \t]*([0-9]+[ \t]+){2}EOS([ \t].*)?"; */
    pattern="[ \t]*BOS([ \t].*)?";
  else
    pattern=argv[1];

  if(argc < 3)
    eoln='\f';
  else
    eoln=atoi(argv[2]);

  if(regcomp(&re, pattern, REG_EXTENDED|REG_NOSUB) !=0)
  {
    fprintf(stderr,"Invalid pattern.\n");
    exit(1);
  }

  while(fgets(buf,5000,stdin))
  {
    buf[strlen(buf)-1]='\0';
    if(firstline)
      firstline=0;
    else
      if(regexec(&re, buf, (size_t)0, NULL, 0) == 0)
        putchar('\n');
      else
        putchar(eoln);
    fputs(buf,stdout);
  }
  putchar('\n');
}