#include <iostream>
#include <fstream>
#include <vector>
#define nrmax 100005
using namespace std;
ifstream in("dfs.in");
ofstream out("dfs.out");
int n, m, contor;
bool check[100005];
vector <int> g[nrmax];
void read(){
    in >> n >> m;
    for (int i=1;i<=n;++i){
        int x, y;
        in>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
        }
}
void dfs(int node){
    check[node]=true;
    int nrvecini=g[node].size();
    for (int i=0;i<nrvecini;++i){
        int  next_node = g[node][i];
        if (check[next_node] == false)
            dfs(next_node);
    }
}
void nr_count(){
    for (int i=1;i<=n;++i)
        {
        if (check[i] == false)
            {
            ++contor;
            dfs(i);
            }
        }
}
int main()
{
    read();
    nr_count();
    out << contor;

    return 0;
}