Close numbers#457
In developing a data analysis system, you are given the following partial task. You have a set of integers (initially empty) and a sequence of queries of three types:
ADD x — add the element to the set (if such an element already exists, the set does not change).
DEL x — remove the element from the set (if such an element does not exist, the set does not change).
FIND — find and output the minimal distance between any two closest elements in the set. It is guaranteed that the set contains at least two elements at this point.
Process the given sequence of queries.
The first line contains one integer (1 \le N \le 100\ 000): the total number of queries. Each of the next lines contains one query in the format described above. All numerical values in the queries are in the range from to .
For each query of type FIND, output one number: the distance between the two closest elements in the set at that moment (one number per line).
Example 1