'''
@author : saitejaedate
'''
# Write a python program to find the square root of the given number
# using approximation method

# testcase 1
# input: 25
# output: 4.999999999999998

# testcase 2
# input: 49
# output: 6.999999999999991

def main():
    # ep_silon and step are initialized
    # don't change these value
    # your code starts here
    '''
    python program to find the square root of the given number
    '''
    x_num = int(input())
    ep_silon = 0.01
    lo_wer = 0.0
    high_er = x_num
    bi_val = (high_er + lo_wer)/2.0
    while abs(bi_val**2 - x_num) > ep_silon:
        if bi_val**2 < x_num:
            lo_wer = bi_val
        else:
            high_er = bi_val
        bi_val = (high_er + lo_wer)/2.0
    print(bi_val)

if __name__ == "__main__":
    main()
