#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <unistd.h>
#include <regex.h>

char *
get_stdin(void)
{
	static char *buf;
	const size_t siz = 32*1024;	// 32 KB should be enough for everyon, right? ^-^
	if (!(buf = malloc(siz))) {
		err(1, 0);
	}
	if (read(STDIN_FILENO, buf, siz) >= (ssize_t)siz) {
		errx(1, "read");
	}
	return buf;
}

char *
get_regex_error(int code)
{
	switch (code) {
	case 0:            return "Success, not an error";
	case REG_NOMATCH:  return "The regexec() function failed to match";
	case REG_BADPAT:   return "invalid regular expression";
	case REG_ECOLLATE: return "invalid collating element";
	case REG_ECTYPE:   return "invalid character class";
	case REG_EESCAPE:  return "‘\\’ applied to unescapable character";
	case REG_ESUBREG:  return "invalid backreference number";
	case REG_EBRACK:   return "brackets ‘[ ]’ not balanced";
	case REG_EPAREN:   return "parentheses ‘( )’ not balanced";
	case REG_EBRACE:   return "braces ‘{ }’ not balanced";
	case REG_BADBR:    return "invalid repetition count(s) in ‘{ }’";
	case REG_ERANGE:   return "invalid character range in ‘[ ]’";
	case REG_ESPACE:   return "ran out of memory";
	case REG_BADRPT:   return "‘?’, ‘*’, or ‘+’ operand invalid";
	case REG_EMPTY:    return "empty (sub)expression";
	case REG_ASSERT:   return "cannot happen - you found a bug";
	case REG_INVARG:   return "invalid argument, e.g. negative-length string";
	case REG_ILLSEQ:   return "illegal byte sequence (bad multibyte character)";
	}
	return "Unknown error code";
}

int
main(void)
{
	char *buf;
	int code, enable, result;
	regex_t preg;
	regmatch_t pmatch[4];
	buf = get_stdin();
	if ((code = regcomp(&preg, "(don't\\(\\)|do\\(\\)|mul\\(([0-9]+),([0-9]+)\\))", REG_EXTENDED))) {
		errx(1, "regcomp %s", get_regex_error(code));
	}
	result = 0;
	enable = 1;
	while (regexec(&preg, buf, 4, pmatch, 0) == 0) {
		switch (*(buf + pmatch[0].rm_so + 2)) {	// Check third character because it is unique
		case '(':	// do()
			enable = 1;
			break;
		case 'n':	// don't()
			enable = 0;
			break;
		case 'l':	// mul()
			result += enable *
			          atoi(buf + pmatch[2].rm_so) *
			          atoi(buf + pmatch[3].rm_so);
			break;
		}
		buf += pmatch[0].rm_eo;
	}
	printf("%u\n", result);
	return 0;
}