Математички израз

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.NoSuchElementException;

interface Stack<E> {

    // Elementi na stekot se objekti od proizvolen tip.

    // Metodi za pristap:

    public boolean isEmpty ();
    	// Vrakja true ako i samo ako stekot e prazen.

    public E peek ();
    	// Go vrakja elementot na vrvot od stekot.

    // Metodi za transformacija:

    public void clear ();
    	// Go prazni stekot.

    public void push (E x);
    	// Go dodava x na vrvot na stekot.

    public E pop ();
    	// Go otstranuva i vrakja elementot shto e na vrvot na stekot.
}

class ArrayStack<E> implements Stack<E> {
    private E [] elems; //niza na elementi koi odat od 0 do depth-1
    private int depth; //dlabochina na stekot

    public ArrayStack(int maxDepth){
        elems=(E[]) new Object[maxDepth]; //kreirash niza so maxDepth golemina
        depth=0;
    }

    public boolean isEmpty() {
        return depth==0;
    }

    @Override
    public E peek() {
        if(depth==0)
            throw new NoSuchElementException();
        return elems[depth-1]; //posledniot element se naogja na depth-1
    }

    @Override
    public void clear() {
        for (int i=0;i<depth;i++){
            elems[i]=null;
        }
        depth=0;
    }

    @Override
    public void push(E x) {
        elems[depth++]=x; //se dodava elementot na pozicija depth bidejki toa e naredno slobodno i se zgolemuva depth
    }

    @Override
    public E pop() {
        if(depth==0)
            throw new NoSuchElementException();
        E topmost=elems[--depth]; //depth e naredniot sloboden a --depth e posledniot element
        elems[depth]=null;
        return topmost;
    }
}


public class ExpressionEvaluator {

	public static int evaluateExpression(String expression){
		ArrayStack<Integer> stack=new ArrayStack<Integer>(100);
        String broj="";
        int flagM=0;

        for(int i=0;i<expression.length();i++){
            int pushed=0;
            char znak=expression.charAt(i);

            if(Character.isDigit(znak)){
                broj+=znak;
                if((i+1)==expression.length() || !Character.isDigit(expression.charAt(i+1))){
                    stack.push(Integer.valueOf(broj).intValue());
                    broj="";
                    pushed=1;
                }
            }

            if(znak=='*'){
                flagM=1;
                continue;
            }

            if(flagM==1 && pushed==1){
                int num1=stack.pop();
                int num2=stack.pop();
                int result=num1*num2;
                stack.push(result);
                flagM=0;
            }
        }

        int suma=0;
        while (!stack.isEmpty()){
            suma+=stack.pop();
        }
        return suma;

	}
	public static void main(String[] args) throws IOException {
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		System.out.println(evaluateExpression(input.readLine()));
	}

}