package JavaAdvancedRetakeExam03May2017;

import java.math.BigDecimal;
import java.math.MathContext;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class LetterExpression {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine();
        String[] words = input.replaceFirst("[0-9]+", "").split("[0-9]+");
        String[] numbers = input.split("[^0-9]+");
        BigDecimal sum = new BigDecimal("0");
        for (int i = 0; i < numbers.length; i++) {
            BigDecimal currentNum = new BigDecimal("0");
            currentNum = new BigDecimal(numbers[i].trim());
            if (i == 0) {
                sum = currentNum;
                continue;
            }
            try {
                words[i - 1].length();
            } catch (Exception e) {
                sum = sum.subtract(currentNum);
                break;
            }
            if (words[i - 1].length() % 2 == 0) {
                sum = sum.add(currentNum);
            } else {
                sum = sum.subtract(currentNum);
            }
        }
        MathContext mc = new MathContext(0);
        sum = sum.round(mc);
        System.out.println(sum);
    }
}