#include <iostream>
#include <string>
#include <cmath>
#include <list>

int charToInt(char c) {
	return c - '0';
}

int check(char c)
{
	return (c == '2' || c == '3' || c == '4' || c == '+' || c == '*') ? 1 : 0;
}

int calculate(char op, int a, int b) {
	if (op == '+') {
		return a + b;
	}
	else if (op == '*') {
		return a * b;
	}
}

int result(std::string string) {
	std::list<int> stack;

	for (int i = 0; i < string.length(); i++) {
		char token = string[i];

		if (!check(token)) return -1;

		if (token >= '0' && token <= '9') {
			stack.push_back(charToInt(token));
		}
		else {
			int a = stack.back();
			stack.pop_back();
			int b = stack.back();
			stack.pop_back();
			int result = calculate(token, a, b);
			stack.push_back(result);
		}

	}

	return stack.back();
};

int main()
{
	std::string string;

	setlocale(LC_ALL, "russian");

	std::cout << "Ваше выражение: " << std::endl;
	std::cin >> string;

	std::cout << result(string) << std::endl;

	system("pause");
}