How to calculate the team size?

[Victor Smith]

I have a dataset as below. There are two columns, one is the team ID, the other is the team member ID. I want to create a column to represent the team size. In other words, the number of unique member ID in each team. Does anyone know how to do it?

cls
clear all
input team member
1    1
1    1
1    1
1    2
1    2
1    2
1    3
1    3
1    3
1    4
1    4
1    4
2    5
2    5
2    6
2    6
2    6
2    7
3    9
3    9
3    10
3    10
end

What I would like to have is:

input team member size
1    1    4
1    1    4
1    1    4
1    2    4
1    2    4
1    2    4
1    3    4
1    3    4
1    3    4
1    4    4
1    4    4
1    4    4
2    5    3
2    5    3
2    6    3
2    6    3
2    6    3
2    7    3
3    9    2
3    9    2
3    10    2
3    10    2
end

[FernandoRios]

This may help

bysort team member:gen flag=(_n==1)
bysort team :egen size=sum(flag)