# Problem D

Bob

Little Bob is a famous builder. He bought land and wants to build a house. Unfortunately, the problem is the land’s terrain, it has a variable elevation.

The land is shaped like a *rectangle*, $N$ meters wide and $M$ meters long. It can be divided
into $N\cdot M$ squares
(see the image). Bob’s house will be shaped like a
*rectangle* that has sides *parallel* with the
land’s edges and its vertices *coincide* with the
vertices of the squares. All the land covered by Bob’s house
must be of *equal elevation* to prevent it from
collapsing.

Calculate the number of ways Bob can build his house!

## Input

The first line of input contains integers $N$ and $M$ ($1 \leq N, M \leq 1\, 000$).

Each of the following $N$ lines contains $M$ integers $a_{ij}$ ($1 \leq a_{ij} \leq 10^9$), respectively the height of each square of land.

Warning: Please use faster input methods beacuse the amount
of input is very large. For example, either set
`ios::sync_with_stdio(false)` or use `scanf`
instead of `cin` in C++, and use `BufferedReader`
instead of `Scanner` in Java.

## Output

The first and only line of output must contain the required number from the task statement.

Sample Input 1 | Sample Output 1 |
---|---|

5 3 2 2 2 2 2 1 1 1 1 2 1 2 1 2 1 |
27 |

Sample Input 2 | Sample Output 2 |
---|---|

4 3 1 1 1 1 1 1 2 2 2 2 2 2 |
36 |