#include <iostream>
#include <vector>
#include <fstream>
using namespace std;

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

void DFS(int poz,int conex, int viz[], vector <int> graf[])
{
    int n = graf[poz].size();
    viz[poz] = conex;
    for(int i = 0; i < n; ++i)
        if(viz[graf[poz][i]] == 0)
            DFS(graf[poz][i], conex, viz, graf);
}
int main()
{
    int x, y;
    int n, m;
    f>>n>>m;
    vector <int> graf[n];
    for(int i = 0; i < m; ++i)
    {
        f>>x>>y;
        graf[x].push_back(y);
        graf[y].push_back(x);
    }

    int viz[n] = {0};
    int conex = 1;
    for(int i = 1; i < n; ++i)
        if(viz[i] == 0)
        {
            DFS(i, conex, viz, graf);
            conex++;
        }
    g<<conex;
    return 0;
}