#include <stdio.h>

/*
 * phpscrubber:
 * Compile and feed this program data using stdin.
 *
 * It will echo all output to stdout except for anything that looks 
 * like it's in a PHP code block: <? ... ?>
 *
 * The parser's fairly basic, performs no lookahead, and doesn't recognize
 * certain cases (e.g. <script language="php"> isn't treated as a start tag).
 * However, it should correctly recognize that a ?> tag isn't a valid
 * closing tag if it's inside a line comment, etc.
 */

/* '<' indicates possible start of PHP code block (if next char is '?') */
int seen_lt = 0;
/* '?' indicates possible end of PHP code block (if next char is '>') */
int seen_qm = 0;
/* This flag indicates whether we're currently in a PHP code block */
int in_php = 0;

/*
 *  '/' indicates the possible start of a line comment (if next char is '/')
 *  or the possible start of a block comment (if next char is '*')
 */
int seen_fs = 0;
/* '\' indicates the next character might be escaped */
int seen_bs = 0;
/* '*' indicates the possible end of a block comment (if next char is '/') */
int seen_star = 0;

/* Are we in a ' ... ' quote? */
int in_php_single_quote = 0;
/* Are we in a " ... " quote? */
int in_php_double_quote = 0;
/* Are we in ` ... ` instruction? */
int in_php_backticks = 0;
/* Are we in a // ... or # ... line comment? */
int in_php_line_comment = 0;
// Are we in a /* ... */ block comment?
int in_php_block_comment = 0;


int main()
{
    char c;
    while((c = getchar()) != EOF)
    {
        if (!in_php)
        {
            if (seen_lt)
            {
                if (c=='?')
                {
                    in_php = 1;
                    seen_lt = 0;
                }
                else
                {
                    printf("<");
                    seen_lt = c=='<';
                    if (!seen_lt) printf("%c", c);
                }
            }
            else if (c=='<')
            {
                seen_lt = 1;
            }
            else
            {
                printf("%c", c);
            }
        }
        else
        {
            /*
             *  The following tests check if we're in a comment
             *  or quote. If that's the case, a ?> doesn't
             *  indicate the end of a PHP code block
             */

            /* Test for start of line comment */
            if ((c=='#') && !in_php_block_comment && 
                !in_php_single_quote && !in_php_double_quote &&
                !in_php_backticks)
            {
                in_php_line_comment = 1;
            }
            else if ((c=='/') && seen_fs && !in_php_block_comment && 
                     !in_php_single_quote && !in_php_double_quote && 
                     !in_php_backticks)
            {
                in_php_line_comment = 1;
            }

            /* Test for start of block comment */
            else if ((c=='*') && seen_fs && !in_php_line_comment && 
                     !in_php_single_quote && !in_php_double_quote &&
                     !in_php_backticks)
            {
                in_php_block_comment = 1;
            }

            /*
             *  Test for end of line comment
             *  (both line feed and carriage return)
             */
            else if (((c=='\n') || (c=='\r')) && in_php_line_comment)
            {
                in_php_line_comment = 0;
            }

            /* Test for end of block comment */
            else if ((c=='/') && seen_star && in_php_block_comment)
            {
                in_php_block_comment = 0;
            }

            /* Test for start or end of single quote */
            else if ((c=='\'') && !seen_bs && !in_php_double_quote &&
                     !in_php_line_comment && !in_php_block_comment &&
                     !in_php_backticks)
            {
                in_php_single_quote = !in_php_single_quote;
            }

            /* Test for start or end of double quote */
            else if ((c=='"') && !seen_bs && !in_php_single_quote &&
                     !in_php_line_comment && !in_php_block_comment &&
                     !in_php_backticks)
            {
                in_php_double_quote = !in_php_double_quote;
            }

            /* Test for start or end of system command in backticks */
            else if ((c=='`') && !in_php_single_quote &&
                     !in_php_double_quote && !in_php_line_comment &&
                     !in_php_block_comment)
            {
                in_php_backticks = !in_php_backticks;
            }

            if (seen_qm)
            {
                if (c=='>')
                {
                    seen_qm = 0;
                    /*
                     * Exit PHP mode (i.e. set in_php to false)
                     * if we're not in a comment or quote
                     */
                    if (!in_php_line_comment && !in_php_block_comment &&
                        !in_php_single_quote && !in_php_double_quote &&
                        !in_php_backticks)
                    {
                        in_php = 0;
                    }
                }
                else
                {
                    seen_qm = c=='?';
                }
            }
            else if (c=='?')
            {
                seen_qm = 1;
            }
            /* else don't write anything: we're in PHP mode */

            /*
             * The following will always be set to "false" upon
             * leaving a PHP code block, because the char c
             * is always '>' when that happens
             * (we want them to be "false", so that's fine)
             */
            seen_fs = c=='/';
            seen_bs = c=='\\';
            seen_star = c=='*';
        }
    }
    return 0;
}