1	import numpy as np
     2	import matplotlib.pyplot as plt
       
     3	# theta goes from 0 to 2pi
       
     4	theta = np.linspace(0, 2*np.pi, 100)# the radius of the circle
       
     5	x = eval(input("please input a size of the circle:"))
     6	r = np.sqrt (int(x))
       
     7	# compute x1 and x2
     8	x1 = r*np.cos(theta)
     9	x2 = r*np.sin(theta)
       
    10	# create the figure
    11	fig, ax = plt.subplots(1)
    12	ax.plot(x1, x2)
    13	ax.set_aspect(1)
    14	plt.show()
       
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