Problem B
Einkaþjálfari

Eyþrúður has started offering gym classes as a private instructor. Each class is exactly one hour, so it’s not so complicated to make sure classes don’t overlap.

What is more complicated is tracking her available hours in a more broad sense, just to make sure she has enough time left over for sleep, errands and relaxation. Thus she now asks you to implement a computer system that she can register the classes to.

It has to support adding classes, removing classes and checking how many free hours she has between two times $T_1$ and $T_2$

Input

The first line of input contains an integer $q$, the number of queries that will follow. Next there are $q$ lines, each containing one query. Each of them starts with A, D or F. If the line starts with A a time $T$ follows, this denotes that someone wants to book a class at time $T$. If there is already a time booked at time $T$ this query should be ignored. If the line starts with D a time $T$ follows, this denotes that someone wants to remove their class at time $T$. If there is no class at time $T$ this query should be ignored. Finally if the line starts with F two times $T_1$ and $T_2$ follow. Then the program should output the number of hours from $T_1$ to $T_2$ which have not been booked, both ends being inclusive. It will always hold that $T_1 \leq T_2$.

All times in the input are at least $0$ and at most $10^9$.

Output

For each query in the input starting with F the number of available hours should be printed, as described above.

Scoring

10
A 1
A 12
A 17
A 1
F 12 17
F 3 4
D 1
D 1
F 0 100
F 12 12

4
2
99
0