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## 문제

In order to improve their physical fitness, the cows have taken up gymnastics! Farmer John designates his favorite cow Bessie to coach the $N$ other cows and to assess their progress as they learn various gymnastic skills.

In each of $K$ practice sessions ($1 \leq K \leq 10$), Bessie ranks the $N$ cows according to their performance ($1 \leq N \leq 20$). Afterward, she is curious about the consistency in these rankings. A pair of two distinct cows is consistent if one cow did better than the other one in every practice session.

Help Bessie compute the total number of consistent pairs.

## 입력

The first line of the input file contains two positive integers $K$ and $N$. The next $K$ lines will each contain the integers $1 \ldots N$ in some order, indicating the rankings of the cows (cows are identified by the numbers $1 \ldots N$). If $A$ appears before $B$ in one of these lines, that means cow $A$ did better than cow $B$.

## 출력

Output, on a single line, the number of consistent pairs.

## 예제 입력 1

3 4
4 1 2 3
4 1 3 2
4 2 1 3


## 예제 출력 1

4


## 힌트

The consistent pairs of cows are $(1,4)$, $(2,4)$, $(3,4)$, and $(1,3)$.