Informatica Depth Analysis

I have 4 million records in my source as a flat file . i want to load the records to target. Target has four table . In the mapping , first record should go to firat table , second record will go to second table, 3rd record goes to 3rd table, 4th record goes to 4th table , Again 5th record goes to first table and then Continue the same process . How can u do this ?

Logic :: Use four conditions in Router transformation

FIRST::NEXTVAL%2 = 0.5 OR NEXTVAL % 4 = 1
SECOND::NEXTVAL % 4 = 2
THIRD::NEXTVAL % 2 = 1.5 OR NEXTVAL%4 = 3
FOURTH::NEXTVAL %4 = 0