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


for x in range (1,min(len(A),len(B))):
    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:
                for index in range (len(itemA)):
                    print (itemA[index], itemB[index], sep=" ", end= " ")
                print("")