Given a String S, reverse the string without reversing its individual words. Words are separated by dots.

Example 1:

Input:
S = i.like.this.program.very.much
Output: much.very.program.this.like.i
Explanation: After reversing the whole
string(not individual words), the input
string becomes
much.very.program.this.like.i

Example 2:

Input:
S = pqr.mno
Output: mno.pqr
Explanation: After reversing the whole
string , the input string becomes
mno.pqr

Your Task:
You dont need to read input or print anything. Complete the function reverseWords() which takes string S as input parameter and returns a string containing the words in reversed order. Each word in the returning string should also be separated by '.' 

Expected Time Complexity: O(|S|)
Expected Auxiliary Space: O(|S|)

Constraints:
1 <= |S| <= 2000