#include <iostream>

using namespace std;
/*
 * Writes a character string backward.
 * @pre The string s contains size characters,
 *      where size >= 0.
 * @post None.
 * @param s  The string to write backward.
 * @param size  The length of s.
 */
void writeBackward(string s, int size)
{
   if (size > 0)
   {  // write the last character
      cout << s.substr(size-1, 1);

      // write the rest of the string backward
      writeBackward(s, size-1);  // Point A
   }  // end if

   // size == 0 is the base case - do nothing
}  // end writeBackward

int main()
{
  string str;

  cout << "Enter a string to reverse: ";
  cin >> str;
  cout << "The reverse string is: ";
  writeBackward(str, str.length());
  //for(int i=str.length()-1 ; i>=0 ; i--)
  //  cout << str[i];
  cout << endl;
  
  return 0;
}