#include <iostream>
#include <vector>
#include <fstream>
#define limit 100000
using namespace std;

vector <int> v[limit];
bool viz[limit];
int m, n, elemente=0;

void dfs (int x)
{
    viz[x]=1;
    for (int i = 0; i < int(v[x].size()); i++)
        if (v[x][i] != 0 && viz[x]==0) dfs(i);

}

int main()
{
    ifstream fin ("dfs.in");
    ofstream fout ("dfs.out");
    fin>> m>> n;
    for (int i = 1; i <= m; i++)
    {
        int x, y;
        fin>>x >>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for (int i = 1; i <= n; i++)
        if (viz[i] == 0)
        {
            dfs(i);
            elemente++;
        }
    fout<<elemente;
    return 0;
}