//http://www.infoarena.ro/problema/dfs
#include <iostream>
#include <fstream>

using namespace std;

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

int n, G[20000][20000], viz[100000];

void Read()
{
    int x, y, m;
    f >> n >> m;
    for(int i = 1; i <= n; i++)
        f >> x >> y, G[x][y] = G[y][x] = 1;
}

void DFS(int nod)
{
    viz[nod] = 1;
    for(int i = 1; i <= n; i++)
        if(viz[i] == 0 && G[nod][i] == 1)
            DFS(i);
}

int main()
{
    int k = 1;
    Read();
    DFS(1);
    for(int i = 2; i <= n; i++)
        if(!viz[i])
            DFS(i), k++;
    g << k;
    return 0;
}