Count Faults

Observe each server's own requests separately; after three consecutive error results, replace the server and reset its consecutive error count to zero, and a success also resets it. Logs from other servers do not interrupt a server's consecutive requests.

输入格式

The first line contains n m; each of the next m lines contains a server number (1-based) and success/error. 1≤n≤200, 1≤m≤20000.

输出格式

Output a single integer answer.

样例 1

输入：

2 6
1 error
1 error
2 error
1 error
1 error
2 success

输出：

1

样例 2

输入：

1 6
1 error
1 error
1 error
1 error
1 error
1 error

输出：

2

样例 3

输入：

1 4
1 error
1 success
1 error
1 error

输出：

0

样例说明

Example 1: s1 is replaced once when its third error occurs, followed by only one more error, so the answer is 1. Example 2: six errors in a row cause a replacement every three, so the answer is 2. Example 3: a success interrupts the consecutive errors, so the answer is 0.