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

char usage[] = "usage: %s -len file ...\n";
char *pname;

void pad(FILE *f, int len);

int
main(argc, argv)
int argc;
char **argv;
   {
   int len;
   FILE *f;

   pname = argv[0];
   if (argc-- > 1 && **++argv == '-') {
      len = atoi(&argv[0][1]);
      if (len <= 0) {
	 fprintf(stderr, usage, pname);
	 exit(1);
	 }
      argc--;
      }
   else
      len = 80;
   if (argc == 0) {
      pad(stdin, len);
      exit(0);
      }
   while (argc--) {
      ++argv;
      if (**argv == '-')
	 f = stdin;
      else
	 f = fopen(*argv, "r");
      if (f == NULL)
	 fprintf(stderr, "%s: cannot open %s\n", pname, *argv);
      else {
	 pad(f, len);
	 fclose(f);
	 }
      }
   exit(0);
   }

void
pad(f, len)
FILE *f;
int len;
   {
   register int c, w;

   w = 0;
   while ((c = getc(f)) != EOF) {
      switch (c) {
	 case '\t':
	    w = (w | 07) + 1;
	    break;
	 case '\b':
	    if (w) w--;
	    break;
	 case '\n':
	    while (w++ < len)
	       putchar(' ');
	    w = 0;
	    break;
	 default:
	    w++;
	 }
      putchar(c);
      }
   if (w) {
      while (w++ < len)
	 putchar(' ');
      putchar('\n');
      }
   return ;
   }