customer Head1 month1 amount1 head2 month2 amount2 head3 month3 amount3
A1 Tag1 jan 1000 tag2 feb 2000 tag3 mar 1500
B1 flag1 jan 300 flag2 feb 200 flag3 apr 350


i want to convert it into following:

A1 tag1 jan 1000
A1 tag2 feb 2000
A1 tag3 mar 1500
B1 Flag1 jan 300
B2 Flag2 Feb 200
B3 Flag3 apr 350


How to do that????