#include <iostream>
#include <cctype>

enum { MAX_SIZE = 1000 };
char *x;


void inc_exp(){
	std::cout << "ERROR: incorrect expression.\n";
	std::exit(1);
}


int parseFactor() {
	while (isspace(*x)) {
		x++;
	}
	int value = 0, sign = 1;
	if (*x == '+' || *x == '-') {
		if (*x == '-') {
			sign = -1;
		}
		x++;
	}
	while (isspace(*x)) {
		x++;
	}
	if (isdigit(*x)) {
		while (isdigit(*x)) {
			value = value * 10 + *x - '0';
			x++;
		}
		return sign * value;
	}
	else {
		inc_exp();
	}
}

int parseMultDiv() {

	int fac1 = parseFactor();

	while (*x == '*' || *x == '/') {
		char temp = *x;
		x++;
		int fac2 = parseFactor();
		if (temp == '*') {
			fac1 *= fac2;
		}
		else {
			if (fac2 == 0) inc_exp();
			fac1 /= fac2;
		}

	}
	return fac1;
}

int parseSumSub() {

	int pro1 = parseMultDiv();

	while (*x == '+' || *x == '-') {
		int sign = 1;
		if (*x == '-') sign = -1;
		++x;
		int pro2 = parseMultDiv();
		pro1 = pro1 + sign * pro2;

	}
	if (*x != '\0') {
		inc_exp();
	}
	return pro1;
}

int main(int argc, char **argv) {
	char norm_exp[MAX_SIZE];
	x = norm_exp;
	if (argc == 1) {
		inc_exp();
	}
	for (int i = 1; i < argc; i++) {
		for (int j = 0; j < len(argc[i]); j++) {
			*x++ = argc[j];
		}
	}
	if (*(x - 1) != '\"' || norm_exp != '\"') {
		inc_exp();
	}
	*(x - 1) = '\0';
	x = norm_exp + 1;
	std::cout << parseSumSub();
	return 0;
}