First there are ways to give the tickets out without any restrictions whatsoever.

Now think this way. Give person three a ticket to show three.

So we have reduced the problem.

There are ways to give those remaining tickets out without any restrictions whatsoever.

But we must remove from that number the cases in which person oneorperson two got a ticket not wanted. Use inclusion/exclusion:

.

That is the number of ways in which at least one of the two got a ticket not wanted.