> d = {'a': 1, 'b': 2, 'c': 3}
> def invert_dict(d):
...   return dict([(v,k) for (k,v) in d.iteritems()])
...
> invert_dict(d)
{1: 'a', 2: 'b', 3: 'c'}

> d = {'a': 1, 'b': 2, 'c': 3, 'd': 4}
> from itertools import izip
> def invert_dict(d):
...   return dict(izip(d.itervalues(), d.iterkeys()))
...
> invert_dict(d)
{1: 'a', 2: 'b', 3: 'c', 4: 'd'}
>

dict=eval(input()) #输入格式：dict = {"a":1,"b":2}
dict_new={}
try:
  for k,v in dict.items():
    dict_new[v]=k
  print(dict_new)
except:
  print("输入错误")