Find area of circle and square using Pure Virtual Function

#include <iostream.h>
#include<conio.h>

class Shape                    /* Abstract class */
{
    protected:
       float l;
    public:
       void get_data()          /* Note: this function is not virtual. */
       {
  cin>>l;
       }

       virtual float area() = 0; /* Pure virtual function */
};

class Square : public Shape
{
    public:
       float area()
       {   return l*l;  }
};

class Circle : public Shape
{
    public:
       float area()
       { return 3.14*l*l; }
};

void main()
{
    Square s;
    Circle c;
    cout<<"Enter length to calculate area of a square: ";
    s.get_data();
    cout<<"Area of square: "<<s.area();
    cout<<"\nEnter radius to calcuate area of a circle:";
    c.get_data();
    cout<<"Area of circle: "<<c.area();

    getch();
}