import java.util.*;
import java.io.*;

@SuppressWarnings("unused")
public class Main {

  private static class DisjointSet {
    public int[] upper; // minus:num_element(root) plus:root(normal)
  //	public int[] w;
    
    public DisjointSet(int n)
    {
      upper = new int[n];
      Arrays.fill(upper, -1);
  //		w = new int[n];
    }
    
    public DisjointSet(DisjointSet ds)
    {
      this.upper = Arrays.copyOf(ds.upper, ds.upper.length);
    }		
    
    public int root(int x)
    {
      return upper[x] < 0 ? x : (upper[x] = root(upper[x]));
    }
    
    public boolean equiv(int x, int y)
    {
      return root(x) == root(y);
    }
    
    public boolean union(int x, int y)
    {
      x = root(x);
      y = root(y);
      if(x != y) {
        if(upper[y] < upper[x]) {
          int d = x; x = y; y = d;
        }
  //			w[x] += w[y];
        upper[x] += upper[y];
        upper[y] = x;
      }
      return x == y;
    }
    
    public int count()
    {
      int ct = 0;
      for(int u : upper){
        if(u < 0)ct++;
      }
      return ct;
    }
    
    public int[][] toBucket()
    {
      int n = upper.length;
      int[][] ret = new int[n][];
      int[] rp = new int[n];
      for(int i = 0;i < n;i++){
        if(upper[i] < 0)ret[i] = new int[-upper[i]];
      }
      for(int i = 0;i < n;i++){
        int r = root(i);
        ret[r][rp[r]++] = i;
      }
      return ret;
    }
  }
  
  private static void solve() {
    int n = ni();
    int m = ni();

    var ds = new DisjointSet(n * 2);
    for (int i = 0; i < m; i ++) {
      ds.union(ni()-1, ni()-1);
    }

    int ret = 0;
    for (int i = 0; i < n * 2; i ++) {
      if (i == ds.root(i)) {
        ret += -ds.upper[i] / 2;
      }
    }
    ret = n * 2 - ret * 2;
    System.out.println(ret / 2);
  }

  public static void main(String[] args) {
    new Thread(null, new Runnable() {
      @Override
      public void run() {
        solve();
        out.flush();
      }
    }, "", 64000000).start();
  }

  private static PrintWriter out = new PrintWriter(System.out);
  private static StringTokenizer tokenizer = null;
  private static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in), 32768);

  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());
  }
}