I have the following DataFrame

Input:

```
A    B    C    D    E
2    3    4    5    6
1    1    2    3    2 
2    3    4    5    6

```

I want to add a new column that has the minimum of A, B and C for that row

Output:

```
A    B    C    D    E    Goal
2    3    4    5    6    2
1    1    2    3    2    1 
2    3    4    5    6    2

```

I have tried to use 

```
df = df[['A','B','C]].min() 

```

but I get errors about hashing lists and also I think this will be the min of the whole column I only want the min of the row for those specific columns.

How can I best accomplish this?