Problem Statement

Joisino is planning to record N TV programs with recorders.
The TV can receive C channels numbered 1 through C.
The i-th program that she wants to record will be broadcast from time s_i to time t_i (including time s_i but not t_i) on Channel c_i.
Here, there will never be more than one program that are broadcast on the same channel at the same time.
When the recorder is recording a channel from time S to time T (including time S but not T), it cannot record other channels from time S-0.5 to time T (including time S-0.5 but not T).
Find the minimum number of recorders required to record the channels so that all the N programs are completely recorded.

Input

Input is given from Standard Input in the following format:
N C
s_1 t_1 c_1
:
s_N t_N c_N

Output

When the minimum required number of recorders is x, print the value of x.

Constraints

• 1≤N≤10^5
• 1≤C≤30
• 1≤s_i<t_i≤10^5
• 1≤c_i≤C
• If c_i=c_j and i≠j, either t_i≤s_j or s_i≥t_j.
• All input values are integers.

Sample Input 1

3 2
1 7 2
7 8 1
8 12 1

Sample Output 1

2

Two recorders can record all the programs, for example, as follows:

• With the first recorder, record Channel 2 from time 1 to time 7. The first program will be recorded. Note that this recorder will be unable to record other channels from time 0.5 to time 7.
• With the second recorder, record Channel 1 from time 7 to time 12. The second and third programs will be recorded. Note that this recorder will be unable to record other channels from time 6.5 to time 12.

Sample Input 2

3 4
1 3 2
3 4 4
1 4 3

Sample Output 2

3

There may be a channel where there is no program to record.

Sample Input 3

9 4
56 60 4
33 37 2
89 90 3
32 43 1
67 68 3
49 51 3
31 32 3
70 71 1
11 12 3

Sample Output 3

2

见题面 Input 部分

见题面 Output 部分