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
import sys

input=sys.stdin.readline

N,M=map(int,input().split())
eat=[]
for i in range(M):
    x,y=map(int,input().split())
    eat.append((x,y))

eat=eat[::-1]

turkey=[]
for i in range(1,N+1):
    tempval=set([i])
    tempid=set([])
    for j in range(M):
        x,y=eat[j]
        if x in tempval and y in tempval:
            break
        elif x in tempval:
            tempval.add(y)
            tempid.add(j)
        elif y in tempval:
            tempval.add(x)
            tempid.add(j)
    else:
        turkey.append([tempval,tempid])

ans=0
n=len(turkey)
#print(turkey)
for i in range(1,n):
    for j in range(i):
        aval,aid=turkey[i]
        bval,bid=turkey[j]
        checkval=True
        checkid=True
        for val in bval:
            checkval=checkval&(val not in aval)
        for id in bid:
            checkid=checkid&(id not in aid)
        if checkid and checkval:
            ans+=1
            #print(i,j)

print(ans)