#include <bits/stdc++.h>

using namespace std;
ifstream fin("dfs.in");
ofstream fout("dfs.out");
const int nmax = 100005;
int n, m, nr;
bool vizitat[nmax];
vector < int > Muchii[nmax];
void dfs(int nod)
{
    vizitat[nod] = true;
    for(int i = 0; i < Muchii[nod].size(); ++i)
    {
        int x = Muchii[nod][i];
        if(!vizitat[x])
            dfs(x);
    }
}
void read()
{
    fin >> n >> m;
    for(int i = 1; i <= n; ++i)
    {
        int x,y;
        fin >> x >> y;
        Muchii[x].push_back(y);
        Muchii[y].push_back(x);
    }
    for(int i = 1; i <= n; ++i)
    {
        if(!vizitat[i])
        {
            nr++;
            dfs(i);
        }
    }
}
int main()
{
    read();
    fout << nr << "\n";
    return 0;
}