#include <iostream>
#include <fstream>
#include <vector>

#define DN 100005

using namespace std;

vector<int> list[DN];

bool viz[DN];

ifstream f("dfs.in");
ofstream g("dfs.out");

void dfs(int nod){
    viz[nod]=true;
    for(int j=0;j<list[nod].size();++i)
    {
        int next_nod=list[nod][j];
        if(viz[next_nod]==0)
            dfs(next_nod);
    }
}

int main()
{
    int c=0;
    f>>n>>m;
    for(int i=1;i<=n;++i)
    {
        int a,b;
        f>>a>>B;
        list[a].push_back(b);
        list[b].push_back(a);
        for (int j=1;j<=m;++j)
        {
            if(viz[j]==0){
                dfs(j);
                ++c;
            }
        }
    }
    g<<c;
    return 0;
}