class Solution {
    public List<String> readBinaryWatch(int num) {
        ArrayList<String> result = new ArrayList<>();
        for(int i=0; i<12; i++)
        {
            for(int j=0; j<60; j++)
            {
                if(Integer.bitCount(i) + Integer.bitCount(j) == num)
                    result.add(String.format("%d:%02d",i,j));
            }
        }
        return result;
    }
}