Python-Min/max of seq WITHOUT min() and max()

Given a sequence such as x = [5, 9, 0, -14], I need to find the min and max without sorting the sequence or by using min() and max().  I've been instructed to use loop constructs, but I can't figure out how to do so.  Help is greatly appreciated.

>>9
You can easily add an int, float or long subclass that supports infinity.

Start like:
class PosInfinityType: pass
PosInfinity = PosInfinityType()
class NegInfinityType: pass
NegInfinity = NegInfinityType()

Then go on like:
class iint(int):

and redefine all the special methods (double underscored div, add, eq, lt, etc, check the docs). It's pretty easy.