public static HashMap countString(String input){
		//use hashtable for threads
		HashMap<Character, Integer> result = new HashMap<Character, Integer>();
		//128 size for standard ascii code, change size for different coding
		int[] tmp = new int[128];
		for (char c : input.toCharArray()){
			tmp[(int)c]++;
		}
		for(int i = 0; i <tmp.length; i++){
			if(tmp[i] > 1)
				result.put((char)i,tmp[i]);
		}
		return result;
	}