#include<bits/stdc++.h>
using namespace std;
#define ll long long int
int in=-1;
int n, m;
vector<vector<int> > edges;
vector<int> dp, tin, parent;
vector<int> cnt;
int tt = 0, ans = 0, total;
vector<bool> vis;
vector<bool> cond;
int diam = 0;
void df(int u,int par=-1)
{
    vis[u]=true;
    for(ll v : edges[u])
    {
        if(!vis[v])
            df(v,u);
        else if(v!=par && vis[v])
            in=v;
    }
}

void dfs(int u, int par = -1){
    tin[u] = tt++;
    vis[u] = true;
    for(auto v : edges[u]){
        if(v == par)    continue;
        if(!vis[v]){
            dfs(v, u);
            dp[u] += dp[v];
        }
        else if(tin[v]<tin[u])    dp[u]++, cond[u] = false;
        else if(tin[v] > tin[u])    dp[u]--, cond[u] = false;
        cond[u]= cond[u] & cond[v];
    }
    if(dp[u] != 0 or par == -1)  cond[u] = false;
    if(!cond[u])    return;

    for(auto v : edges[u]){
        if(v == par)    continue;
        parent[v] = u;
    }
    parent[u] = u;
}

int coun;
void process(int u, int par = -1){
    vis[u] = true;
    int high = 0, s_high = 0;
    for(auto v : edges[u]){

        if(parent[v] == -1) continue;
        if(!vis[v]){
            process(v);
            int tmp = cnt[v] + (dp[v] == 0);
          //  cout << u << ":" << v << " " << tmp << "\n";
            total += (dp[v] == 0);
            if(high <= tmp)  s_high = high, high = tmp;
            else if(tmp >= s_high)   s_high = tmp;
            cnt[u] = max(cnt[u], tmp);
        }
    }
    coun++;
    diam = max(diam, high + s_high);
}

int main()
{
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
 //   freopen("output.txt","w", stdout);
    #endif
    edges.clear();
        cin >> n >> m;
        edges.resize(n+1);
        dp.clear();
        dp.resize(n+1, 0);
        tin.clear();
        tin.resize(n+1);
        vis.clear();
        vis.resize(n+10, false);
        cnt.clear();
        cnt.resize(n+1, 0);
        int u, v;
        for(int i = 0; i < m; i++)  {
            cin >> u >> v;
            edges[u].push_back(v);
            edges[v].push_back(u);
        }
        df(1);
        vis.clear();
        vis.resize(n+1, false);
       if(in==-1)
            cout<<n;
        else
        {
            cond.resize(n+1, true);
            parent.resize(n+1, -1);
            dfs(in,-1);
            diam = 0;
            int cur = 0, tmp = 0;
            vis.clear();
            vis.resize(n+1, false);
            for(int i = 1; i <= n; i++){
                if(parent[i] == i and dp[i] == 0){
                    diam = 0;
                    coun = 0;
                    process(i);
                    if(diam >= cur)  cur = diam, tmp = coun;
                }
            }
            cout << tmp << "\n";
        }

}