# Arup Guha
# 1/5/2013
# Solution to Programming Knights Practice Program Chapter 1 Problem 1
# Circle Radius

import math

PI = 3.141592654

def main():
    
    # Get the circle area.
    area = float(input("What is the area of your circle, in square feet?\n"))

    # Calculate radius and output result.
    radius = math.sqrt(area/PI);
    print("Your circle's radius is",radius,"feet.");

main()