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

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return std::vector(arg, init);
    else return std::vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

int par[200000 + 1];

void init() {
    fill(begin(par), end(par), -1);
}

int root(int x) {
    if (par[x] < 0) {
        return x;
    }
    return par[x] = root(par[x]);
}

void unite(int x, int y) {
    x = root(x);
    y = root(y);
    if (x == y) return;
    par[x] += par[y];
    par[y] = x;
}

bool same(int x, int y) {
    return root(x) == root(y);
}

int size(int x) {
    return -par[root(x)];
}

int main() {
    init();

    int n, m; cin >> n >> m;
    auto a = vec<int>(uns, n, 0);
    for (int i = 0; i < n; ++i) {
        int b, c; cin >> b >> c; --b; --c;
        a[c].push_back(b);
    }

    for (auto &b : a) {
        for (int i = 1; i < b.size(); ++i) {
            unite(b[i - 1], b[i]);
        }
    }

    int ans = 0;
    for (int i = 0; i < m; ++i) {
        if (same(i, m)) continue;
        ans += size(i) - 1;
        unite(i, m);
    }

    cout << ans << endl;
}