/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2021.02.12 21:52:18
**/

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


class UnionFind {
private:
    vector<int> par;
public:
    UnionFind(int n) {
        par.resize(n, -1);
    }
    int root(int x) {
        if (par[x] < 0) return x;
        return par[x] = root(par[x]);
    }
    bool unite(int x, int y) {
        int rx = root(x);
        int ry = root(y);
        if (rx == ry) return false;
        if (size(rx) < size(ry)) swap(rx, ry);
        par[rx] += par[ry];
        par[ry] = rx;
        return true;
    }
    bool same(int x, int y) {
        int rx = root(x);
        int ry = root(y);
        return rx == ry;
    }
    int size(int x) {
        return -par[root(x)];
    }
};
int main() {
    int n,m;cin >> n >> m;
    UnionFind uf(m);
    vector<int> a(n,-1);
    for (int i = 0; i < n; i++) {
        int b,c;cin >> b >> c;
        b--;c--;
        if (a[c] != -1) {
            uf.unite(a[c],b);
        }
        a[c] = b;
    }
    ll total = 0;
    for (int i = 0; i < m; i++) {
        if (uf.root(i) == i) {
            total += uf.size(i) - 1;
        }
    }
    cout << total << endl;
    return 0;
}