#include "bits/stdc++.h"
using namespace std;

using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = (ll)1e9 + 7;
struct UnionFind {
	vector<int>par, vsize, esize;
	UnionFind(int sz_) : par(sz_), vsize(sz_, 1), esize(sz_, 0) {
		for (int i = 0; i < sz_; i++)par[i] = i;
	}
	void init(int sz_) {
		par.resize(sz_);
		vsize.resize(sz_, 1);
		esize.resize(sz_, 0);
		for (int i = 0; i < sz_; i++)par[i] = i;
	}
	int root(int x) {
		if (par[x] == x)return x;
		else return par[x] = root(par[x]);
	}
	bool merge(int x, int y) {
		x = root(x), y = root(y);
		if (x == y) {
			esize[x]++;
			return false;
		}
		if (vsize[x] < vsize[y])swap(x, y);
		vsize[x] += vsize[y];
		esize[x] += esize[y] + 1;
		par[y] = x;
		return true;
	}
	bool issame(int x, int y) {
		return root(x) == root(y);
	}
	int vs(int x) {
		return vsize[root(x)];
	}
	int es(int x) {
		return esize[root(x)];
	}
};
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll N, M; cin >> N >> M;
	vector<ll>b(N), c(N);
	vector<vector<ll>>a(N);
	for (int i = 0; i < N; i++) {
		cin >> b[i] >> c[i]; b[i]--; c[i]--;
		a[c[i]].push_back(b[i]);
	}
	UnionFind uf(M);
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < (int)a[i].size() - 1; j++) {
			int now = a[i][j], nx = a[i][j + 1];
			if (now != nx) {
				uf.merge(now, nx);
			}
		}
	}
	set<int>st;
	for (int i = 0; i < M; i++) {
		st.insert(uf.root(i));
	}
	ll ans = 0;
	for (auto x : st) {
		ans += uf.vs(x) - 1;
	}
	cout << ans << endl;
	return 0;
}