def solution(orders, course):
    
    def sorting(data):
        temp = []
        for i in data:
            temp += i

        temp.sort()
        value = ''
        
        for m in temp:
            value += m

        return value

    
    def combination(order, number):
        
        order_set = []
        
        if number <= 1:
            return order
        
        for m in range(len(order)):
            for n in combination(order[m+1:], number -1):
                order_set.append(sorting(order[m]+n))
        
        return order_set
        
# ---------------------------------------------------
    
    answer = []
    for number in course:
        set = []
        for order in orders:
            set += combination(order, number)
        
        count = 2
        selected_course = []
        for i in set:
            if count <= set.count(i):
                if count == set.count(i):
                    selected_course += [i]
                    continue
                count = set.count(i)
                selected_course = [i]
            
        
        
        answer += selected_course
        
    temp = ''
    temp_answer = []
    answer.sort()
    for i in answer:
        if temp == i:
            continue
        temp = i
        temp_answer.append(i)


    answer = temp_answer
    
    
    
    return answer