Count Similar Pairs

Two strings are similar if they contain the same set of letters; how many times each letter occurs does not matter. Identical strings at different indices can still form a pair, and (i,j) and (j,i) are counted only once.

输入格式

The first line contains n, followed by n lines of lowercase strings. 1≤n≤100000, total length ≤10^6. The original text does not exclude empty strings; this site's protocol supports an empty line representing an empty string.

输出格式

Output one integer, the answer.

样例 1

输入：

3
xyz
foo
of

输出：

1

样例 2

输入：

2

输出：

1

样例 3

输入：

4
ab
aab
b
ba

输出：

3

样例说明

The examples give 1, 1 and 3 respectively.