import java.util.*;

public class Main {
    public static void main(String args[]) {
        Scanner scan = new Scanner(System.in);
        String line;
        while (scan.hasNextLine()) {
            line = scan.nextLine().trim();
            // please write your code here
            System.out.println(Main.calculate(line));
        }
    }
    private static String calculate(String s){
        LinkedList<Integer> list = new LinkedList();
        char [] c = new char[s.length()+1];
        for(int i=0;i<c.length-1;i++) c[i] = s.charAt(i);
        c[c.length-1] = ‘+‘;///为下面运算准备，当前运算符的运算要检测到下一个运算符才运算

        int num=0;
        char pre=‘X‘;///初始化
        int temp;
        boolean flag = false;
        for(int i=0;i<c.length;i++){
            if(c[i]==‘ ‘) continue;
            if(flag) break;
            if(c[i]>=‘0‘&&c[i]<=‘9‘) num = num*10+c[i]-‘0‘;///一位位地把数字符转换为数字
            else{///，运算符进行运算的时间是在检测到下一个运算符才能运算
                switch (pre){///这个运算符是之前的
                    case ‘+‘:
                          list.push(num);
                          break;
                    case ‘-‘:
                          list.push(num*(-1));
                          break;
                    case ‘*‘:
                          temp=(list.pop()*num);
                          list.push(temp);
                          break;
                    case ‘/‘:
                        if(num==0) {flag=true;break;}///分母为0
                        temp=(list.pop()/num);
                        list.push(temp);
                        break;
                    default:
                        list.push(num);
                        break;
                }
                pre = c[i];///存下当前的符号，为下一次运算
                num=0;///num归0
            }
        }
        if(flag) return "err";
        int sum=0;
        while(list.size()!=0) sum+=list.pop();
        return sum+"";
    }
}