import java.util.Arrays;

public class Main {
  private static void solve() {
    int n = ni();
    int m = ni();
    int[] from = new int[m];
    int[] to = new int[m];
    for (int i = 0; i < m; i ++) {
      from[i] = ni() - 1;
      to[i] = ni() - 1;
    }
    int[][] g = packU(n, from, to);
    
    int[] v = decomposeToBECC(g);
    int ret = Arrays.stream(v).max().getAsInt();
    
    System.out.println(ret);
    
  }

  public static int[][] packU(int n, int[] from, int[] to){ return packU(n, from, to, from.length); }
  public static int[][] packU(int n, int[] from, int[] to, int sup)
  {
      int[][] g = new int[n][];
      int[] p = new int[n];
      for(int i = 0;i < sup;i++)p[from[i]]++;
      for(int i = 0;i < sup;i++)p[to[i]]++;
      for(int i = 0;i < n;i++)g[i] = new int[p[i]];
      for(int i = 0;i < sup;i++){
          g[from[i]][--p[from[i]]] = to[i];
          g[to[i]][--p[to[i]]] = from[i];
      }
      return g;
  }
  
  public static int[] decomposeToBECC(int[][] g)
  {
      int n = g.length;
      boolean[] visited = new boolean[n];
      int[] ord = new int[n];
      int[] low = new int[n];
      
      int[] ids = new int[n];
      int[] inds = new int[n];
      int[] parct = new int[n];
      int pos = 0;
      for(int i = 0;i < n;i++){
          if(!visited[i]){
              ids[0] = i;
              inds[0] = 0;
              int sp = 1;
              while(sp > 0){
                  int cur = ids[sp-1];
                  if(inds[sp-1] == 0){
                      visited[cur] = true;
                      ord[cur] = low[cur] = pos++;
                      parct[sp-1] = 0;
                  }
                  if(inds[sp-1] == g[cur].length){
                      if(sp-2 >= 0)low[ids[sp-2]] = Math.min(low[ids[sp-2]], low[cur]);
                      sp--;
                      continue;
                  }
                  int next = g[cur][inds[sp-1]];
                  if(!visited[next]){
                      ids[sp] = next;
                      inds[sp] = 0;
                      inds[sp-1]++;
                      sp++;
                      continue;
                  }else if(sp-2 >= 0 && (next != ids[sp-2] || ++parct[sp-1] >= 2)){
                      low[cur] = Math.min(low[cur], ord[next]);
                  }
                  inds[sp-1]++;
              }
          }
      }
      
      int[] clus = new int[n];
      Arrays.fill(clus, -1);
      int[] q = new int[n];
      int cnum = 0;
      for(int i = 0;i < n;i++){
          if(clus[i] == -1){
              int p = 0;
              q[p++] = i;
              clus[i] = cnum++;
              for(int r = 0;r < p;r++){
                  int cur = q[r];
                  for(int next : g[cur]){
                      if(clus[next] == -1){
                          clus[next] = ord[cur] < low[next] ? cnum++ : clus[cur];
                          q[p++] = next;
                      }
                  }
              }
          }
      }
      return clus;
  }
  public static void main(String[] args) {
    new Thread(null, new Runnable() {
      @Override
      public void run() {
        long start = System.currentTimeMillis();
        String debug = args.length > 0 ? args[0] : null;
        if (debug != null) {
          try {
            is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
        reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);
        solve();
        out.flush();
        tr((System.currentTimeMillis() - start) + "ms");
      }
    }, "", 64000000).start();
  }

  private static java.io.InputStream is = System.in;
  private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);
  private static java.util.StringTokenizer tokenizer = null;
  private static java.io.BufferedReader reader;

  public static String next() {
    while (tokenizer == null || !tokenizer.hasMoreTokens()) {
      try {
        tokenizer = new java.util.StringTokenizer(reader.readLine());
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
    return tokenizer.nextToken();
  }

  private static double nd() {
    return Double.parseDouble(next());
  }

  private static long nl() {
    return Long.parseLong(next());
  }

  private static int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }

  private static char[] ns() {
    return next().toCharArray();
  }

  private static long[] nal(int n) {
    long[] a = new long[n];
    for (int i = 0; i < n; i++)
      a[i] = nl();
    return a;
  }

  private static int[][] ntable(int n, int m) {
    int[][] table = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[i][j] = ni();
      }
    }
    return table;
  }

  private static int[][] nlist(int n, int m) {
    int[][] table = new int[m][n];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[j][i] = ni();
      }
    }
    return table;
  }

  private static int ni() {
    return Integer.parseInt(next());
  }

  private static void tr(Object... o) {
    if (is != System.in)
      System.out.println(java.util.Arrays.deepToString(o));
  }
}




Measured memory_bytes: 27732