# SQ2.py  computes a square root of a nonnegative int.
# input: a nonnegative int
# output: a nonnegative square root or an error message

import math

num = int(raw_input("Type an int: "))

if num >= 0 :
    # assert: num is nonnegative; it has a square root:
    print math.sqrt(num)
else :
    # assert: num is < 0 (negative)
    print "Sorry --- cannot compute square root of a negative number"

print  # a blank line
raw_input("press Enter to finish")