def aOrB(k, a, b, c):  
    # Convert a, b, c to (0-left-padded) binary arrays
    bin_len = 4*max(map(len, [a, b, c]))
    a_bin, b_bin, c_bin = map(lambda x: [*map(int, f'{int(x, 16):0>{bin_len}b}')], [a, b, c])
    
    # First pass: perform minimal bit changes to satisfy a'|b'==c
    a_new, b_new = [], []
    for x, y, z in zip(a_bin, b_bin, c_bin):
        if (x | y) ^ z == 1:
            if (x | y) == 0:
                y = 1  # only change bit in b, to keep a' minimal
                k -= 1
            else:
                k -= x+y
                x, y = 0, 0
        a_new.append(x)
        b_new.append(y)
    
    # If after initial pass k<0, then no solution
    if k < 0:
        print(-1)
    else:
        # If k>0, can look for further minimizations
        for i in range(bin_len):
            if k == 0:
                break
            elif (a_new[i], b_new[i]) == (1, 1):
                a_new[i] = 0
                k -= 1
            elif ((a_new[i], b_new[i]) == (1, 0)) and (k > 1):
                a_new[i], b_new[i] = 0, 1
                k -= 2
        
        a_new_hex, b_new_hex = map(lambda x: hex(int(''.join(map(str, x)), 2))[2:].upper(), [a_new, b_new])
        print('\n'.join([a_new_hex, b_new_hex]))