import itertools
A=[10, 20, 30,40]
B=[11,21,31,41]
list_solutions = []


for x in range (1,min(len(A),len(B))+1):
    newA = list(itertools.combinations(A,x))
    newB = list(itertools.combinations(B,x))
    for itemA in newA:
        for itemB in newB:
            to_print = True
            for index in range (min(len(itemA),len(itemB))):
                if itemA[index] >= itemB[index]:
                    to_print = False
                    break
            if to_print == True:
                list_solutions.append([itemA, itemB])

#Print only valid solutions:
for item in list_solutions:
    print_valid = True
    for index in range (len(item[0])):
        if item[0][index] >= item[1][index]:
            print_valid = False
            break
        if index >= 1:
            if item[0][index] <= item[1][index-1]:
                print_valid = False
                break
    if print_valid == True:
        for index in range (len(item[0])):
            print (item[0][index], item[1][index], sep = " ", end = " ")
        print ("")
    if print_valid == False:
        continue