import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        HashMap<Integer, HashSet<Integer>> counts = new HashMap<>();
        for (int i = 0; i < n; i++) {
            int b = sc.nextInt();
            int c = sc.nextInt();
            if (!counts.containsKey(c)) {
                counts.put(c, new HashSet<>());
            }
            counts.get(c).add(b);
        }
        int ans = 0;
        for (HashSet<Integer> set : counts.values()) {
            ans += set.size() - 1;
        }
        System.out.println(ans);
    }
}