#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cctype>
#include <cstring>
#include <inttypes.h>

using namespace std;

class Recurs_descent_calc {
    public:
        bool there_was_error;
        int64_t count_up(char* str_expr) {
            expr = str_expr;
            return add();
        }
        Recurs_descent_calc(): there_was_error(false) {}
    private:
        char* expr;
        void eat_up_next_spaces() { for(; expr[0] == ' '; expr++); }
        int64_t add() {
            eat_up_next_spaces();
            int64_t counted = sub();
            eat_up_next_spaces();
            if(*expr == '+') { expr++; return counted + add(); }
            return counted;
        }
        int64_t sub() {
            eat_up_next_spaces();
            int64_t counted = mul_div();
            eat_up_next_spaces();
            if(*expr == '-') { expr++; return counted - sub(); }
            return counted;
        }
        int64_t mul_div() {
            eat_up_next_spaces();
            int64_t counted = minus();
            eat_up_next_spaces();
            if(*expr == '*') { expr++; return counted * mul_div(); }
            if(*expr == '/') {
                expr++;
                int64_t divider = mul_div();
                if(divider != 0) return counted / divider;
                there_was_error = true;
            }
            return counted;
        }
        int64_t minus() {
            eat_up_next_spaces();
            if(*expr == '-') {
                expr++;
                return -1 * num(); //Может ли быть много ун. минусов подряд?
            }
            return num();
        }
        int64_t number_of_digits(int64_t num) {
            int64_t q;
            for(q = 0; num != 0; q++) num = num / 10;
            return q;
        }
        int64_t num() {
            eat_up_next_spaces();
            int64_t number;
            if(sscanf(expr, "%" SCNd64, &number)) {
                expr += number_of_digits(number);
                eat_up_next_spaces();
                return number;
            }
            there_was_error = true;
        }
};

int main(int argc, char* argv[]) {
    int64_t result;
    Recurs_descent_calc calc;                   //Create a calculator instance
    if(argc != 2) calc.there_was_error = true;  //Сheck the correctness of input
    else result = calc.count_up(argv[1]);       //Feed him the entered expr to calculate
    if(calc.there_was_error) {                  //Сheck the correctness of calculation
        cout << "error" << '\n';
        return 1;
    }
    cout << result << '\n';
    return 0;
}