# 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")