#include<bits/stdc++.h>
#define FILE "read"
#define MAXN 3010
#define INF 1000000000
using namespace std;
struct node{int y,next,v,rel;}e[9010];
int n,m,len,ans,S,T,value(1),Link[MAXN],level[MAXN],a[MAXN],temp[MAXN],hash[MAXN][5];
queue<int>q;
char buf[1<<15],*fs,*ft;
inline char getc(){return (fs==ft&&(ft=(fs=buf)+fread(buf,1,1<<15,stdin),fs==ft))?0:*fs++;}
inline int read(){
	int x=0,f=1;  char ch=getc();
	while(!isdigit(ch))  {if(ch=='-')  f=-1;  ch=getc();}
	while(isdigit(ch))  {x=x*10+ch-'0';  ch=getc();}
	return x*f;
}
void insert(int x,int y,int v){
	e[++len].next=Link[x];Link[x]=len;e[len].y=y;e[len].v=v;e[len].rel=len+1;
	e[++len].next=Link[y];Link[y]=len;e[len].y=x;e[len].v=v;e[len].rel=len-1;
}
bool bfs(){
	memset(level,-1,sizeof(level));
	q.push(S);  level[S]=0;
	while(!q.empty()){
		int x=q.front(); q.pop();
		for(int i=Link[x];i;i=e[i].next)
			if(level[e[i].y]==-1&&e[i].v){
				q.push(e[i].y);
				level[e[i].y]=level[x]+1;
			}
	}
	return level[T]>=0;
}
int MAXFLOW(int x,int flow){
	if(x==T)  return flow;
	int d=0,maxflow=0;
	for(int i=Link[x];i&&maxflow<flow;i=e[i].next)
		if(level[e[i].y]==level[x]+1&&e[i].v)
			if(d=MAXFLOW(e[i].y,min(e[i].v,flow-maxflow))){
				e[i].v-=d; e[e[i].rel].v+=d; maxflow+=d;
			}
	if(!maxflow)  level[x]=-1;
	return maxflow;
}
void solve(int l,int r){
	if(l==r)  return;
	S=a[l];  T=a[r];  int d=0,ans=0;
	for(int i=1;i<=len;++i) e[i].v=e[e[i].rel].v=(e[i].v+e[e[i].rel].v)>>1;
	while(bfs()) while(d=MAXFLOW(S,INF))  ans+=d;
	value*=233; for(int i=1;i<=n;++i) if(level[i]==-1) hash[i][ans]+=value;
	int ta=l,tb=r;
	for(int i=l;i<=r;++i){
		if(level[a[i]]>=0)  temp[ta++]=a[i];
		else temp[tb--]=a[i];
	}
	for(int i=l;i<=r;++i)  a[i]=temp[i];
	solve(l,ta-1);  solve(tb+1,r);
}
int main(){
	freopen(FILE".in","r",stdin);
	freopen(FILE".out","w",stdout);
	n=read();  m=read();
	for(int i=1;i<=m;++i){
		int x=read(),y=read();
		insert(x,y,1);
	}
	for(int i=1;i<=n;++i)  a[i]=i;
	solve(1,n);
	for(int i=1;i<=n;++i)for(int j=i+1;j<=n;++j)for(int k=0;k<=3;++k)
		if(hash[i][k]!=hash[j][k])  {ans+=k;  break;}
	printf("%d\n",ans);
	return 0;
}