How many beers can you drink?

beer.py

#!/usr/bin/python

def drink_beer():
        global caps
        global empties
        global full
        caps += 1
        empties += 1
        full -= 1
        print "Drank full bottle.\n"

def trade_empties():
        global caps
        global empties
        global full
        global total
        empties -= 2
        full += 1
        total += 1
        print "Traded in two empty bottles.\n"

def trade_caps():
        global caps
        global empties
        global full
        global total
        caps -= 4
        full +=1
        total += 1
        print "Traded in four bottle caps.\n"

# start with 5 full, unopened bottles (10/2)
empties = 0
full = 5
caps = 0
total = 5

while (1):
        while (empties >= 2):
                trade_empties()
        while (caps >= 4):
                trade_caps()
        drink_beer()
        print "empty bottles:", empties
        print "caps held:", caps
        print "Total bottles:", total, "\n"
        if (empties < 2 and caps < 4 and full <= 0):
                print "Nothing to trade or drink.  Passing out.\n\n"
                exit(0)