#include "stdio.h"
#include "fcntl.h"

main (argc,argv)
int argc;
char *argv[];
  {
int f;
long offset;
char buf[10];
long getlong ();
long lret;
long ret;

  if (argc == 3)
    {
/*    offset = strtol (argv[2],(char *)NULL,16);*/
    offset = getlong (argv[2]);
    f = open (argv[1],O_RDWR|O_BINARY);
    if (f != -1)
      {
      lret = lseek (f,offset,0);
      ret = read (f,buf,1);
      lret = lseek (f,offset,0);
      buf[0] ^= 0xff;
      ret = write (f,buf,1);
      close (f);
      }
    }
  }

long getlong (str)
char *str;
  {
long val;

  val = 0;
  sscanf (str,"%lx",&val);
  return (val);

  }