You are given a grid of letters. Your task is to calculate the number of rectangle subgrids that contain all the letters.

Input

The first line has two integers $n$ and $k$: the size of the grid and the number of letters. The letters are the first $k$ uppercase letters.

After this, there are $n$ lines that describe the grid. Each line has $n$ letters.

Output

Print the number of subgrids.

Constraints

• $1 \le n \le 500$
• $1 \le k \le 26$

Example

Input:

5 3
ABBBC
BBBBC
BCAAA
AAAAA
AAAAA

Output:

70