#include <iostream>

#include <cmath>

using namespace std;

int main()

{

   double diameter, radius, length, area;

   const double PI = 3.14159;

   cout << "Enter the diameter of the circle: ";

   cin >> diameter;

   radius = diameter / 2;

   length = 2 * PI * radius;

   area = PI * pow(radius, 2);

   cout << "The length of the circle is " << length << endl;

   cout << "The area of the circle is " << area << endl;

   return 0;

}