#include<iostream>
#define PI 3.1415
int r=2;
void area();
class MyClass
{
    
    public:
    int a;
    void display()
    {
        std::cout<<"inside class"<<std::endl;
    
    }
}    
    int main()
    {
        MyClass m;
        m.a=90;
        m.display();
        area();
        std::cout<<"Hello World"std::endl;
        std::cout<<m.a<<std::endl;
        return 0;
    }
    void area()
    {
        float area;
        area=PI*r*r;
        std::cout<<area<<std::endl;
    }
}