Whenever my friend Alistair writes to me he does so entirely in code. He always uses symbols for letters but changes the code each time, so any particular symbol does not necessarily stand for the same letter of the alphabet every time. I always start to crack the code by looking at how he has written his name at the end of his letter. For instance, last time he was: [symbols showing 'Alistair'] In my last letter to him I asked him when he intends to visit me next. Today I have received a reply consisting of just one word as follows: [symbols showing reply]