def find_last(s, t):
        return max((s.find(t,i) for i in xrange(len(s))))
        
print find_last("aaaa","a")
print find_last("zz", "a")
print find_last('a', 'a')
print find_last("aaaa","a")
print find_last("zz", "a")
print find_last('a', 'a')
print find_last('jkhgdshjksadhjkgfhkjds', '0')
print find_last('bbbbnvcm,jkvcxvxckvkjxcvhjxhjkca', 'a')
print find_last('doo dee doo dee doo', 'dee')