print('**************************************')
print ('Welcome to DumbCAD 1.01')
print ('A Simple Programme to Draw A Regular Polygon')
print ('')

#get "num_sides"
num_sides = int(input("How many sides is the polygon to have: between 3 and 20  ?: "))
x = (num_sides)

#get "length"
length = int(input("What is the length of each side ?"))
print('')

# dictionary of names "polynames"
polynames =	{
  3 : "Triangle",
  4 : "Square",
  5 : "Pentagon",
  6 : "Hexagon",
  7 : "Heptagon",
  8 : "Octagon",
  9 : "Nonagon",
  10: "Decagon",
  11: "Hendecagon",
  12: "Dodecagon",
  13: "Triskaidecagon",
  14: "Tetradecagon",
  15: "Pendedecagon",
  16: "Hexdecagon",
  17: "Heptdecagon",
  18: "Octdecagon",
  19: "Enneadecagon",
  20: "Icosagon",
}
# use "num_sides" to get "figure_name" from dictionary "polynames"
figure_name = polynames[x]

#calculate internal angle of polygon
int_angle = (num_sides-2)*180/num_sides

print (f'Okay, a {num_sides} sided polygon is called a {figure_name} and it has an internal angles of {int_angle} degrees.')
print (f'Lets draw a regular {figure_name} with {length} long sides.')

import turtle
turtle.screensize(4000,4000)
turtle.hideturtle()
turtle.speed(speed=1)
turtle.bgcolor("grey")
turtle.pen(pencolor="blue", pensize=5)

for i in range(num_sides):
    turtle.forward(length)
    turtle.left (180 - (int_angle))

turtle.penup()
label=len(figure_name)
turtle.goto(-label*9+length/2,-60) #start position for text
turtle.write(figure_name, font=("Verdana",25, "normal"))
turtle.Screen().exitonclick()