Check my code for replace pi using recursion

#1

link: https://ide.codingblocks.com/s/86372
i am getting the error of String index out of bounds. Earlier to resolve this issue by changing the base case . but this time i do not understand how to fix this. This occurs many time please tell me how handle this case. is possible give me any other approach to solve this problem.

#2

Hi,take input of string as sc.next instead of sc.nextLine().