/*
Title: String to Integer

Problem statement
Write a recursive function to convert a given string into the number it represents. That is input
will be a numeric string that contains only numbers, you need to convert the string into
corresponding integer and return the answer.

Detailed explanation ( Input/output format, Notes, Images )
Input format :
Numeric string S (string, Eg. "1234")

Output format :
Corresponding integer N (int, Eg. 1234)

Constraints :
0 < |S| > input;
    cout