gistfile1.java

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Mmass {
    static Map<Character, Integer> m = new HashMap<Character, Integer>();
    public static void main(String[] args) {
        m.put('H', 1);
        m.put('C', 12);
        m.put('O', 16);
        String molecule = (new Scanner(System.in)).next();
        System.out.println(compute(molecule,0,0));
    }
    private static int compute(String str, int pos, int acc) {
        if (pos >= str.length()) return acc;
        char c = str.charAt(pos);
        int mass = 0;
        if(c == '(') {
            int brackets = 1;
            StringBuffer tmp = new StringBuffer();
            while (brackets > 0) {
                char x = str.charAt(++pos);
                tmp.append(x);
                if (x == '(') brackets++;
                if (x == ')') brackets--;
            }
            tmp.deleteCharAt(tmp.length()-1);
            mass = compute(tmp.toString(), 0, 0);
        }
        char n = pos < str.length()-1 ? str.charAt(++pos) : '1';
        boolean multiply = Character.isDigit(n);
        if(multiply) pos++;
        acc += (c == '(' ? mass : m.get(c)) * (multiply ? Character.getNumericValue(n) : 1);
        return compute(str, pos, acc);
    }
}