if you need to keep the blank rows you will need to do this,
1. insert a new collumn A with numbered 1,2,3,...,4999,5000
2. insert a new collumn B, with 0 then 1 then 0 then 1 0 1 0 1 0......... do first 3 and drag
3. sort B so you have all 00000s and then 11111s, delete the cells you dont...