#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
vector<pair<int, int>> vec;
int par[200020];
int siz[200020];
int bo[200020] = { false };
int root(int x) {
	if (par[x] == x) {
		return x;
	}
	else {
		return par[x] = root(par[x]);
	}
}
int main() {
	int n, m;
	int x, y;
	cin >> n >> m;
	for (int i = 0; i < m; i++) {
		par[i] = i;
		siz[i] = 1;
	}
	for (int i = 0; i < n; i++) {
		int b, c;
		cin >> b >> c;
		vec.emplace_back(make_pair(c, b--));
	}
	sort(vec.begin(), vec.end());
	for (int i = 1; i < n; i++) {
		if (vec[i - 1].first == vec[i].first) {
			x = root(vec[i-1].second);
			y = root(vec[i].second);
			if (x != y) {
				par[x] = y;
				int mem = siz[x];
				siz[x] += siz[y];
				siz[y] += mem;
			}
		}
	}
	int ans = 0;
	for (int i = 0; i < m; i++) {
		if (!bo[root(i)]) {
			ans += siz[root(i)] - 1;
			bo[root(i)] = true;
		}
	}
	cout << ans << endl;
	return 0;
}