#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define R cin>>
#define ln cout<<'\n'
#define ll long long
#define in(a) insert(a)
#define pb(a) push_back(a)
#define pd(a) printf("%.10f\n",a)
#define mem(a) memset(a,0,sizeof(a))
#define all(c) (c).begin(),(c).end()
#define iter(c) __typeof((c).begin())
#define rrep(i,n) for(ll i=(ll)(n)-1;i>=0;i--)
#define REP(i,m,n) for(ll i=(ll)(m);i<(ll)(n);i++)
#define rep(i,n) REP(i,0,n)
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
ll check(ll n,ll m,ll x,ll y){return x>=0&&x<n&&y>=0&&y<m;}void pr(){ln;}
template<class A,class...B>void pr(const A &a,const B&...b){cout<<a<<(sizeof...(b)?" ":"");pr(b...);}
template<class A>void PR(A a,ll n){rep(i,n)cout<<(i?" ":"")<<a[i];ln;}
const ll MAX=1e9+7,MAXL=1LL<<61,dx[8]={-1,0,1,0,-1,-1,1,1},dy[8]={0,1,0,-1,-1,1,1,-1};
typedef pair<ll,ll> P;

ll p[200001],r[200001],c[200001];
void init(ll n){rep(i,n)p[i]=i,r[i]=0,c[i]=0;}
int find(int x){return (p[x]==x)?x:(p[x]=find(p[x]));}
void unite(int x,int y) {
  x=find(x),y=find(y);
  if(x==y) {
    c[x]++;
    return;
  }
  int cx=c[x],cy=c[y];
  if(r[x]<r[y])p[x]=y;
  else{p[y]=x;if(r[x]==r[y])r[x]++;}
  c[find(x)]=max(cx,cy)+1;
}
bool same(int x,int y){return find(x)==find(y);}

void Main() {
  ll n,m;
  cin >> n >> m;
  P a[m];
  rep(i,m) {
    cin >> a[i].F >> a[i].S;
    a[i].F--,a[i].S--;
  }
  init(n);
  rrep(i,m) unite(a[i].F,a[i].S);
  pr(c[find(0)]);
}

int main(){ios::sync_with_stdio(0);cin.tie(0);Main();return 0;}