# [USACO13JAN]座位Seating

## 题目描述

To earn some extra money, the cows have opened a restaurant in their barn specializing in milkshakes. The restaurant has N seats (1 <= N <= 500,000) in a row. Initially, they are all empty.
Throughout the day, there are M different events that happen in sequence at the restaurant (1 <= M <= 300,000). The two types of events that can happen are:
1. A party of size p arrives (1 <= p <= N). Bessie wants to seat the party in a contiguous block of p empty seats. If this is possible, she does so in the lowest position possible in the list of seats. If it is impossible, the party is turned away.
2. A range [a,b] is given (1 <= a <= b <= N), and everybody in that range of seats leaves.
Please help Bessie count the total number of parties that are turned away over the course of the day.
有一排n个座位，m次操作。A操作：将a名客人安置到最左的连续a个空位中，没有则不操作。L操作：[a,b]的客人离开。
求A操作的失败次数。

## 输入输出格式

### 输入格式

\* Line 1: Two space-separated integers, N and M.
\* Lines 2..M+1: Each line describes a single event. It is either a line of the form "A p" (meaning a party of size p arrives) or "L a b" (meaning that all cows in the range [a, b] leave).

### 输出格式

\* Line 1: The number of parties that are turned away.

## 输入输出样例

### 输入样例 #1

```
10 4
A 6
L 2 4
A 5
A 2
```

### 输出样例 #1

```
1
```

## 说明

There are 10 seats, and 4 events. First, a party of 6 cows arrives. Then all cows in seats 2..4 depart. Next, a party of 5 arrives, followed by a party of 2.
Party #3 is turned away. All other parties are seated.