In ALV I need to color the records when ever material number changes

Hi ,

I need to color the records in alv when ever the material changes.

for ex : I have 10 records .

1 to 3 records same material number so yellow color

4 to 8 records same material numberso blue color

9 to 10 recrods same material number so yellow color.

Please do the favour..

thank you.

karthik.