Similar numbers
In developing the system of data analysis needed to solve the following particular problem. There is a set of integers (initially empty) and a sequence of queries of three types:
ADD x — add an element x in the set (if an element already exists, then the set does not change)
DEL x — delete element x from the set (if no such element, then the set does not change)
FIND — find and display the distance between the two closest elements in the set. This ensures that the set has at least two elements.
Required to fulfill a given sequence of requests.
Input
The first line contains one integer N (1 <= N <= 100 000) — total number of requests. In each of the next N lines of a written request pursuant to the above format. All numeric values in the query are in the range from 1 to 1 000 000 000.
Output
Bring one number in the row for each query type FIND — the distance between the two closest elements in the set at the time of the query.