Converting List of Int Array to Dictionary

Question

I have a list of int array . Say inputList ({1,2,3,4},{2,3,4,5},{7,8,9,0})

How do I convert it into a dictionary with key as concatination of number of int array and value as int array. So, inputDictionary would be like  (1234, {1,2,3,4}) , ...

I am having hard time figuring out on using inputList.ToDictionary method.