private void initializeVariables() {
		variables = new TreeMap<Integer, Integer>();
		variablesSnapshot = new TreeMap<Integer, Integer>();
		// each site has copies of variables with even indexes
		for(int i = 1; i<=10; i++) {
			variables.put(2*i, 20*i);
			variablesSnapshot.put(2*i, 20*i);
		}
		// if the sid of a site is even, it has copies of variables with index (sid-1) or (sid+9)
		if((sid%2) == 0){
			variables.put((sid-1), 10*(sid-1));
			variables.put((sid+9), 10*(sid+9));
			variablesSnapshot.put((sid-1), 10*(sid-1));
			variablesSnapshot.put((sid+9), 10*(sid+9));
		}		
	}