I have the following Data
A B C D
1 X1 10 X2 2
2 X1 15 X3 5
3 X2 5
4 X2 6
5 X3 11
6 X3 17
i need to sort them to look like
A B C D
1 X1 10
2 X1 15
3 X2 5 X2 2
4 X2 6
5 X3 11 X3 5
6 X3 17

My file contain more then 10,000 line