import time,StringIO
 
start = time.time()
s = ""
for i in xrange(50000):
	s += str(i)
print "method 1:",time.time()-start
 
 
start = time.time()
s = []
for i in xrange(50000):
	s.append(str(i))
s = "".join(s)
print "method 2:",time.time()-start
 
 
start = time.time()
s = StringIO.StringIO()
for i in xrange(50000):
	s.write(str(i))
s = s.getvalue()
print "method 3:",time.time()-start
 
"""
method 1: 9.42199993134
method 2: 0.110000133514
method 3: 0.233999967575"""