#include<bits/stdc++.h>
#if __has_include(<atcoder/all>)
#endif
using namespace std;
#define LL(...) ll __VA_ARGS__;lin(__VA_ARGS__)
#define RDVV(T,n,...) vec<T>__VA_ARGS__;fe(refs(__VA_ARGS__),e)e.get().resizes(n);vin(__VA_ARGS__)
#define VV(n,...) RDVV(ll,n,__VA_ARGS__)
#define fo(i,...) for(auto[i,i##stop,i##step]=for_range<ll>(0,__VA_ARGS__);i<i##stop;i+=i##step)
#define of(i,...) for(auto[i,i##stop,i##step]=for_range<ll>(1,__VA_ARGS__);i>=i##stop;i+=i##step)
#define fe(a,e,...) for(auto&&__VA_OPT__([)e __VA_OPT__(,__VA_ARGS__]):a)
#define defpp template<ostream&o=cout>void pp(const auto&...a){[[maybe_unused]]const char*c="";((o<<c<<a,c=" "),...);o<<'\n';}void epp(const auto&...a){pp<cerr>(a...);}
#define entry defpp void main();void main2();}int main(){my::io();my::main();}namespace my{
namespace my{
void io(){cin.tie(nullptr)->sync_with_stdio(0);cout<<fixed<<setprecision(15);}
using ll=long long;
constexpr auto refs(auto&...a){return array{ref(a)...};}
template<class T>constexpr auto for_range(T s,T b){T a=0;if(s)swap(a,b);return array{a-s,b,1-s*2};}
void lin(auto&...a){(cin>>...>>a);}
void vin(auto&...a){fo(i,(a.size()&...))(cin>>...>>a[i]);}
auto max(auto...a){return max(initializer_list<common_type_t<decltype(a)...>>{a...});}
void dec(auto&...a){((--a),...);}
template<class...A>using pack_back_t=tuple_element_t<sizeof...(A)-1,tuple<A...>>;
}
namespace my{
template<class V>constexpr int depth=0;
template<class T>struct core_t_helper{using type=T;};
template<class T>using core_t=core_t_helper<T>::type;
template<class V>struct vec;
template<int D,class T>struct hvec_helper{using type=vec<typename hvec_helper<D-1,T>::type>;};
template<class T>struct hvec_helper<0,T>{using type=T;};
template<int D,class T>using hvec=hvec_helper<D,T>::type;
template<class V>struct vec:vector<V>{
  static constexpr int D=depth<V>+1;
  using C=core_t<V>;
  using vector<V>::vector;
  void resizes(const auto&...a){if constexpr(sizeof...(a)==D)*this=make(a...,C{});else{ }}
  static auto make(ll n,const auto&...a){
    if constexpr(sizeof...(a)==1)return vec<C>(n,array{a...}[0]);
    else { }
  }
  vec&operator--(){fe(*this,e)--e;return*this;}
  ll size()const{return vector<V>::size();}
};
template<class...A>requires(sizeof...(A)>=2)vec(const A&...a)->vec<hvec<sizeof...(A)-2,pack_back_t<A...>>>;
}
namespace my{
class DsuPlain{
public:
  ll n_;
  vec<int>par_or_size_;
  DsuPlain(ll n):n_(n),par_or_size_(n,-1){}
  auto merge(ll a,ll b){
    ll x=leader(a),y=leader(b);
    if(x==y)return x;
    if(-par_or_size_[x]<-par_or_size_[y])swap(x,y),swap(a,b);

    par_or_size_[x]+=par_or_size_[y];
    par_or_size_[y]=x;
    return x;
  }
  auto merge_with_details(ll a,ll b){
    ll x=leader(a),y=leader(b);
    ll z=merge(a,b);
    return z==x?tuple{x,y,a,b}:tuple{y,x,b,a};
  }
  bool same(ll a,ll b){return leader(a)==leader(b);}
  ll leader(ll a){
    if(par_or_size_[a]<0)return a;
    return par_or_size_[a]=leader(par_or_size_[a]);
  }
};
}
namespace my{entry
void main(){
  LL(N,M);
  VV(M,a,b);dec(a,b);

  vec<ll>cnt(N);
  DsuPlain uf(N);
  of(i,M){
    if(uf.same(a[i],b[i])){
      cnt[uf.leader(a[i])]++;
    }
    else{
      auto[nl,ol,_,__]=uf.merge_with_details(a[i],b[i]);
      cnt[nl]=max(cnt[nl],cnt[ol])+1;
    }
  }
  pp(cnt[uf.leader(0)]);
}}