import java.util.Scanner;
import java.util.Arrays;

public class Solution {

	/**
	 * @param args
	 */

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		int tree[];
		int count[];

		Scanner scan = new Scanner(System.in);

		int N = scan.nextInt(); //points
		int M = scan.nextInt();

		tree = new int[N];
		count = new int[N];
		Arrays.fill(count, 1);

		for(int i=0;i<M;i++)
		{
			int u1 = scan.nextInt();
		    int v1 = scan.nextInt();

		    tree[u1-1] = v1;

		    count[v1-1] += count[u1-1];

		    int root = tree[v1-1];

		    while(root!=0)
		    {
		    	count[root-1] += count[u1-1];
		    	root = tree[root-1];
		    }
		}

		System.out.println("");

	    int counter = -1;
		for(int i=0;i<count.length;i++)
		{
			if(count[i]%2==0)
			{
				counter++;
			}

		}
		System.out.println(counter);

	}

}