difference between prinf and in cout?

I tried out this question.. http://www.codechef.com/problems/MARBLEGF

I got AC when i used cin and cout... Submission: http://www.codechef.com/viewsolution/3333732 I wanted to increase the speed so I first tried to replace cin and cout with scanf and printf but I got WA with the changes Submisson: http://www.codechef.com/viewsolution/3333742 . Could anyone please tell me what am I missing here. I did not any other part of the accepted solution. Thanks in advance