package kompanija;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Stack;

public class SLLKompanija {

    // funkcija za presmetuvanje na izrazot pocnuvajki
    // od indeks l, zavrsuvajki vo indeks r
    public static boolean isOperator(char c){
        return (c=='+') || (c=='-');
    }

    static int presmetaj(char c[], int l, int r) {
        Stack<Integer> nums = new Stack<Integer>();
        Stack<Character> ops = new Stack<Character>();
        for (char i: c){
            if(Character.isDigit(i)) nums.push(i-'0');
            if (isOperator(i)) ops.push(i);
        }

        while(true){
            int a = nums.pop();
            int b = nums.pop();
            char o = ops.pop();
            switch(o){
                case('+'): nums.push(a+b);
                break;
                case('-'): nums.push(b-a);
                break;
            }
            int tmp = nums.pop();
            if (nums.isEmpty()) return tmp;
            else nums.push(tmp);
        }

    }

    public static void main(String[] args) throws Exception {
        int i,j,k;

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String expression = br.readLine();
        char exp[] = expression.toCharArray();

        int rez = presmetaj(exp, 0, exp.length-1);
        System.out.println(rez);

        br.close();

    }

}