#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cctype>
#include <cstring>

using namespace std;

class Recurs_descent_calc {
    public:
        int count_up(char* str_expr) {
            expr = str_expr;
            return add_sub();
        }
        void error() {
            cout << "error" << '\n';
            exit(1);
        }
    private:
        char* expr;
        void eat_up_next_spaces() { for(; expr[0] == ' '; expr++); }
        int add_sub() {
            eat_up_next_spaces();
            int counted = mul_div();
            eat_up_next_spaces();
            //if(*expr == '\0') { return counted; }
            if(*expr == '+') { expr++; return counted + add_sub(); }
            if(*expr == '-') { expr++; return counted - add_sub(); }
            //error();
            return counted;
        }
        int mul_div() {
            eat_up_next_spaces();
            int counted = minus();
            eat_up_next_spaces();
            //if(*expr == '\0') { return counted; }
            if(*expr == '*') { expr++; return counted * add_sub(); }
            if(*expr == '/') {
                expr++;
                int divider = add_sub();
                if(divider != 0) return counted / divider;
                else error();
            }
            //error();
            return counted;
        }
        int minus() {
            eat_up_next_spaces();
            if(*expr == '-') {
                expr++;
                return -1 * num(); //Может ли быть много ун. минусов подряд?
            }
            return num();
        }
        int number_of_digits(int num) {
            int q;
            for(q = 0; num != 0; q++) num = num / 10;
            return q;
        }
        int num() {
            eat_up_next_spaces();
            int number;
            if(sscanf(expr, "%d", &number)) {
                expr += number_of_digits(number);
                eat_up_next_spaces();
                return number;
            }
            else error();
        }
};

int main(int argc, char* argv[]) {
    Recurs_descent_calc calc;               //Create a calculator instance
    if(argc != 2) calc.error();             //Сheck the correctness of input
    cout << calc.count_up(argv[1]) << '\n'; //Feed him the entered expr to calculate
    return 0;
}