String Distance

Suppose you are given two strings $$$a$$$ and $$$b$$$. You can apply the following operation any number of times: choose any contiguous substring of $$$a$$$ or $$$b$$$, and sort the characters in it in non-descending order. Let $$$f(a, b)$$$ the minimum number of operations you have to apply in order to make them equal (or $$$f(a, b) = 1337$$$ if it is impossible to make $$$a$$$ and $$$b$$$ equal using these operations).

For example:

• $$$f(\text{ab}, \text{ab}) = 0$$$;
• $$$f(\text{ba}, \text{ab}) = 1$$$ (in one operation, we can sort the whole first string);
• $$$f(\text{ebcda}, \text{ecdba}) = 1$$$ (in one operation, we can sort the substring of the second string starting from the $$$2$$$-nd character and ending with the $$$4$$$-th character);
• $$$f(\text{a}, \text{b}) = 1337$$$.

You are given $$$n$$$ strings $$$s_1, s_2, \dots, s_k$$$ having equal length. Calculate $$$\sum \limits_{i = 1}^{n} \sum\limits_{j = i + 1}^{n} f(s_i, s_j)$$$.