public static void main(String[] args)
    {
        while( 1 > 0)
        {
            ArrayList<Integer> listNumberos = new ArrayList<>();
            ArrayList<Character> listOperador = new ArrayList<>();
            String expressao = getValues();
            if("end-of-file".equals(expressao))
            {
                break;
            }
            processar(expressao, listNumberos, listOperador);
            System.out.println(calcular(listNumberos, listOperador));
        }
    }

    public static String getValues()
    {
        String expressao;
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Write a number and press enter");
        expressao = keyboard.nextLine();
        return expressao;
    }


    public static String processar(String expressao, ArrayList<Integer> listNumberos, ArrayList<Character> listOperador)
    {
        String number = "";
        for(int count = 0; count < expressao.length(); count ++)
        {
            switch(expressao.charAt(count))
            {
                case '+':
                    listNumberos.add(Integer.parseInt(number));
                    listOperador.add('+');
                    number = "0";
                    break;

                case '-':
                    listNumberos.add(Integer.parseInt(number));
                    listOperador.add('-');
                    number = "0";
                    break;

                case '*':
                    listNumberos.add(Integer.parseInt(number));
                    listOperador.add('*');
                    number = "0";
                    break;

                case '/':
                    listNumberos.add(Integer.parseInt(number));
                    listOperador.add('/');
                    number = "0";
                    break;

                case '%':
                    listNumberos.add(Integer.parseInt(number));
                    listOperador.add('%');
                    number = "0";
                    break;

                case ' ':
                    break;

                default:
                    number = number + expressao.charAt(count);
                    break;
            }
        }
        listNumberos.add(Integer.parseInt(number));
        return "";
    }

    public static int calcular(ArrayList<Integer> listNumberos, ArrayList<Character> listOperador)
    {
        int numberX = 0;
        int numberY = 0;
        int calculo = 0;
        for(int count = 0; count < listOperador.size(); count ++)
        {

            switch(listOperador.get(count))
            {
                case '+':
                    if(count == 0)
                    {
                        numberX = listNumberos.get(0);
                        numberY = listNumberos.get(1);
                        calculo = (int) (numberX + numberY);
                    }
                    else
                    {
                        numberX = listNumberos.get(count+1);
                        numberY = calculo;
                        calculo = (int) (numberX + numberY);
                    }
                    break;

                case '-':
                    if(count == 0)
                    {
                        numberX = listNumberos.get(0);
                        numberY = listNumberos.get(1);
                        calculo = (int) (numberX - numberY);
                    }
                    else
                    {
                        numberX = listNumberos.get(count+1);
                        numberY = calculo;
                        calculo = (int) (numberY - numberX);
                    }
                    break;

                case '*':
                    if(count == 0)
                    {
                        numberX = listNumberos.get(0);
                        numberY = listNumberos.get(1);
                        calculo = (int) (numberX * numberY);
                    }
                    else
                    {
                        numberX = listNumberos.get(count+1);
                        numberY = calculo;
                        calculo = (int) (numberY * numberX);
                    }
                    break;

                case '/':
                    if(count == 0)
                    {
                        numberX = listNumberos.get(0);
                        numberY = listNumberos.get(1);
                        calculo = (int) (numberX / numberY);
                    }
                    else
                    {
                        numberX = listNumberos.get(count+1);
                        numberY = calculo;
                        calculo = (int) (numberY / numberX);
                    }
                    break;

                case '%':
                    if(count == 0)
                    {
                        numberX = listNumberos.get(0);
                        numberY = listNumberos.get(1);
                        calculo = (numberX % numberY);
                    }
                    else
                    {
                        numberX = listNumberos.get(count+1);
                        numberY = calculo;
                        calculo = (numberY % numberX);
                    }
                    break;
            }

        }
        return calculo;
    }