Cpp Question : Calculating Price of Eggs

Diary Farm sells organic brown eggs to local customers. They charge Rs 22.50 for a dozen for eggs, or rs 2.10 for individual effs that are not part of a dozen. Write a C++ Program a user for the number of eggs in the order and the displays the amount owned with a full explanation. For Example, typical output might be " You ordered 27 eggs. that's 2 dozens at rs 2.50 per dozen and 3 loose eggs at rs 2.10 each for a total of rs 51.30". The program must iterate until zero is entered for the number of eggs.

Code:

#include<iostream>
    using namespace std;
    int main(void)
    {
     int n;
     float price=0;
     int r=0,q;
     char ch;
     do
     {
      cout<<"\nEnter Numbe of eggs OR zero (0) to exit :";
      cin>>n;
      if(n<0)
      { 
       cout<<"Incorect Value"; 
      } 
      else if(n==0) 
      { 
       exit(0); 
      } 
      else 
      { 
       q=n/12;
       price+=q*22.50; 
       r=n%12; 
       price+=r*2.10; 
      } 
      cout<<"\nThat's "<<q <<" dozen at Rs 22.50 per dozen and "<<r<<" loose eggs at Rs.2.10 each\n"<<"For a total of "<<price;
      cout<<" \nPress y to continue: ";
      cin>>ch;
  }while(ch=='Y' ||ch=='y');
 }

output: