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
#include<bits/stdc++.h>
#define reg register
#define ll long long
using namespace std;
bool s[1005][1005],cnt[1005];
int n,m,a[1000005],b[1000005],ans;
int main()
{
    scanf("%d%d",&n,&m);
    for(reg int i=1;i<=m;i++)scanf("%d%d",&a[i],&b[i]);
    for(reg int i=1;i<=n;i++)
    {
        s[i][i]=1;
        for(reg int j=m;j>=1;j--)
        {
            reg bool x=s[i][a[j]],y=s[i][b[j]];
            if(x&y)
			{
				cnt[i]=1;
				break;
			}
            else if(x)s[i][b[j]]=1;
            else if(y)s[i][a[j]]=1;
        }
    }
    for(reg int i=1;i<n;i++)
    {
        if(cnt[i])continue;
        for(reg int j=i+1;j<=n;j++)
        {
            if(cnt[j])continue;
            reg int tmp=1;
            for(reg int k=1;k<=n;k++)if(s[i][k]&&s[j][k])tmp=0;
            ans+=tmp;
        }
    }
    printf("%d\n",ans);
    return 0;
}