B'This is an easy version of this problem. The only difference between the versions is that you have to solve the hard version in online mode. You can make hacks only if both versions of the problem are solved. You have an array a , which is initially empty. You need to process queries of the following types: The first line contains an integer q ( 1 <= q q <= q 10^6 ) -- the number of queries. The next q lines contain the queries as described above. It is guaranteed that It is also guaranteed that the number of queries of the fourth type (?) does not exceed 10^5 . For each query of the fourth type output one integer -- the number of distinct elements in array a at the moment of query. In the first example array a changes as follows: In the second example array a changes as follows: '...