I am trying to filter duplicate occurrence of number from the input string
If the string contains duplicate characters then it must print "Not a valid number , if the input is without duplicate characters it must print "Valid Number"
What is the correct way to check the duplicate occurrence

```
input_number = raw_input("Please input the number:")
print type(input_number)
if (int(sorted(input_number))):
    print "Not a valid number"
else:
    print "Valid number"

```

I am getting the below error:

```
TypeError: int() argument must be a string or a number, not 'list'

```