There are N turkeys. We number them from 1 through N.

M men will visit here one by one. The i-th man to visit will take the following action:

* If both turkeys x_i and y_i are alive: selects one of them with equal probability, then eats it.
* If either turkey x_i or y_i is alive (but not both): eats the alive one.
* If neither turkey x_i nor y_i is alive: does nothing.



Find the number of pairs (i,\ j) (1 ≤ i < j ≤ N) such that the following condition is held:

* The probability of both turkeys i and j being alive after all the men took actions, is greater than 0.

Constraints

* 2 ≤ N ≤ 400
* 1 ≤ M ≤ 10^5
* 1 ≤ x_i < y_i ≤ N

Input

Input is given from Standard Input in the following format:


N M
x_1 y_1
x_2 y_2
:
x_M y_M


Output

Print the number of pairs (i,\ j) (1 ≤ i < j ≤ N) such that the condition is held.

Examples

Input

3 1
1 2


Output

2


Input

4 3
1 2
3 4
2 3


Output

1


Input

3 2
1 2
1 2


Output

0


Input

10 10
8 9
2 8
4 6
4 9
7 8
2 8
1 8
3 4
3 4
2 7


Output

5
n,m=map(int,input().split())
v=[[1 for i in range(n)] for i in range(n)]
for i in range(m):	
	x,y=map(int,input().split())
	x-=1
	y-=1
	if v[x][y]:
		v[x][y],v[y][x]=0,0
		for j in range(n):
			if v[x][j]==0:
				v[j][y],v[y][j]=0,0
		for j in range(n):
			if v[y][j]==0:
				v[j][x],v[x][j]=0,0
	else:
		for j in range(n):
			v[j][x],v[x][j],v[j][y],v[y][j]=0,0,0,0
print((sum(map(sum,v))-sum([v[i][i] for i in range(n)]))//2)