python 2.7解法
四则运算
http://www.nowcoder.com/questionTerminal/9999764a61484d819056f807d2a91f1e
coding = utf-8
if name == 'main':
a = raw_input()
end = len(a)
s=''
while end > 0:
# print a[end-1]
s=s+a[end-1]
end = end-1
print s
