题目描述

Initially, we have an array of length 1 containing only the number 0. All natural numbers are listed in ascending order in the "reservation list" (the first number in the list is 1). The array undergoes $q$ operations. The $i^{th}$ operation, is one of the following:

• Insert$(p, x)$: Insert the first $x$ numbers from the reservation list after the number $p$ in the array, in ascending order. These numbers are removed from the reservation list.
• Remove$(p, x)$: Remove the next $x$ numbers after number $p$ in the array. These numbers are not returned to the reservation list.

You are given information about $q$ operations, and you are asked to determine the number written in the middle of the array after each operation. If the length of the array after the $i^{th}$ operation is $n$, you should find the $\left\lfloor \frac{n}{2} \right\rfloor^{th}$ element of the array. Note that the indexing of the array starts from 1.

输入格式

The first line contains an integer $q$ ($1 \leq q \leq 5 \cdot 10^5$), which represents the number of operations. Each of the next $q$ lines contains two integers: $p_i$ ($1 \leq p_i \leq 2 \cdot 10^9$), and $k_i$ ($1 \leq |k_i| \leq 2 \cdot 10^9$).

If $k_i = +x$, operation Insert$(p_i, x)$ is executed. If $k_i = -x$, operation Remove$(p_i, x)$ is executed. It is guaranteed that all operations are valid, and no impossible operation is performed on the array. Additionally, at most $2 \cdot 10^9$ numbers are moved from the reservation list into the array.

输出格式

Output $q$ lines. In the $i^{th}$ line, print the middle element of the array after performing the $i^{th}$ operation.

10
0 3
0 2
5 -2
4 1
0 -2
5 2
7 3
3 2
10 5
12 20

1
5
4
6
5
7
9
10
16
22