string[] students = {"Jenna", "Ayesha", "Carlos", "Viktor"};

display_students(students);
display_students(new string[] {"Robert","Vanya"});

void display_students(string[] students) {
    foreach (string student in students) {
        Console.Write($"{student}, ");
    }
    Console.WriteLine();
}

Console.WriteLine();

void print_circle_area(int radius) {
    double area = Math.PI * (radius * radius);
    Console.WriteLine($"Area          = {area:F2}");
}

void print_circle_circumference(int radius) {
    double circumference = 2 * Math.PI * radius;
    Console.WriteLine($"Circumference = {circumference:F2}");
}

void print_circle_info(int radius){
    Console.WriteLine($"Circle with radius {radius}");
    print_circle_area(radius);
    print_circle_circumference(radius);
    Console.WriteLine();
}

//print_circle_area(12);
//print_circle_circumference(12);
print_circle_info(12);
print_circle_info(24);