Actually, I have a dataset about a "meeting". 
For example, A,B,C have a meeting, then the list would be [A,B,C].
Like this, each list would contain a list of members who participated in the meeting.
Therefore:

line1= (A,B,C)

line2= (A,C,D,E)

line3 = (D,F,G)

...

I just would like to count the number how many times each pair of members meet each other.
For example, member A meets C two times from line1 and line2 and member B meets C one time from line1. So, I would like to make a chart like this..

```
    A  B  C  D E F G...

 A  .  1  2  1 ...  

 B  1  . 1  0 

 C

```

...

I thought it would be easy at the first but I am pretty confused.
Please help me and thank you so much in advance.