Bloons Tower Defense 5 - Daily Challenge May 14, 2013 (Dropping Like Flies)(NAPSFRIS)

NAPSFRILLS if I dont leak at round 65 :(

Dropping Like Files - with Snipers, 4/2 Ninjas, and 2/3 Ice Towers, beat Bloon Circles rounds 20-70. No agents allowed. By Squideer

Video is on 3x speed
No Agent, Premium and Speciality
(Please comment if you have better strategy)
For more walkthrough: http://bloons-tower-defense-5.blogspot.com