I want to combine multiple dataframes of unequal length into a new dataframe that has NA values for empty rows. 
e.g. df1
A
1
2
3
4
5
df2
B
1
2
3
4
5
6
Desired output
df3
A  B
1  1
2  2
3  3
4  4
5  5
NA 6
I tired a cbind() but that gives me an error. 
 
    