public class Solution {
    public static void main(String[] args) throws Exception {
        //напишите тут ваш код
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        int inputNumber = 0;
        int total = 0;
        while (true){
            String s = reader.readLine();
            if (s.equals("сумма")){
                break;
            }else{
                inputNumber = Integer.parseInt(reader.readLine());
                total = inputNumber + inputNumber;
            }
        }
        System.out.println(total);
    }
}