Processing math: 100%
Good string pairs - MarisaOJ: Marisa Online Judge

Good string pairs

Time limit: 1000 ms
Memory limit: 256 MB

A pair of strings is considered good if they have at least one common letter. For example, the pair abc and adc is good because they share the letters a and c. Conversely, the pair bc and def is not good because they have no common letters.

Given n strings, count the number of good string pairs.

Input

  • The first line contains an integer n.
  • The next n lines each contain a string.

Output

  • Print the number of good string pairs.

Constraints

  • 1≤n≤105.
  • The strings consist of the first 15 letters of the alphabet and have a length of at most 10 characters.

Example

Input:

4
abc
def
afg
ed

Output:

3