# your code goes here
# your code goes here
def concatenate(*lists):
    lengths = map(len,lists)
    newlen = sum(lengths)
    newlist = [None]*newlen
    start = 0
    end = 0
    for l,n in zip(lists,lengths):
        end+=n
        newlist[start:end] = l
        start+=n
    return newlist

print concatenate("123","456","789")