/* xmlind.c: indent XML text */
#include <stdio.h>

main() {
  register char c;
  register tag = 0; /* in tag */
  register i, indent = 0, blank = 0;

  /* a tag or a maximal text segment is processed at each step */
  for(c = getchar() ; c != EOF;) {
    if(c == '<') { /* tag */
      if((c = getchar()) == '/') { /* end tag */
	indent--;
	if(tag < 0) {
	  putchar('\n');
	  for(i = 0; i < indent; i++)
	    printf("  ");
	} else
	  tag = -1;
	printf("</");
      } else { /* begin tag */
	putchar('\n');
	for(i = 0; i < indent; i++)
	  printf("  ");
	putchar('<');
	putchar(c);
	tag = 1;
	indent++;
      }
      for(c = getchar(); c != '>' && c != EOF;)
	if(c == '\n') {
	  c = getchar();
	  if(c != '>')
	    putchar(' ');
	} else if(c == '/') {
	  putchar('/');
	  if((c = getchar()) == '>' && tag == 1)
	    indent--;
	  tag = -1;
	} else if(c == '"') {
	  putchar('"');
	  for(c = getchar(); c != '"' && c != EOF; c = getchar())
	    putchar(c);
	  if(c == '"') {
	    putchar('"');
	    c = getchar();
	  }
	} else {
	  putchar(c);
	  c = getchar();
	}
      if(c == '>') {
	putchar('>');
	for(c = getchar(); c == '\n' || c == ' '; c = getchar());
      }
    } else { /* text */
      if(tag < 0) { /* just after end tag */
	putchar('\n');
	for(i = 0; i < indent; i++)
	  printf("  ");
      } else
	tag = 0;
      for(blank = 0; c != '<' && c != EOF; c = getchar())
	if(c == '\n' || c == ' ') {
	  if(blank == 0) {
	    putchar(' ');
	    blank = 1;
	  }
	} else {
	  putchar(c);
	  blank = 0;
	}
    }
  }
  putchar('\n');
}