#include <vector>
#include <queue>
#include <fstream>

using namespace std;

int vizitat[100001];

int main()
{
    //ifstream f("dfs.in");
   // ofstream g("dfs.out");

   FILE* f = fopen("dfs.in","r");
   FILE* g = fopen("dfs.out","w");

    vector<int> v[100001];
    queue<int> q;

    int n, m, i, j, x, y, nod, sursa, k = 1, cc = 0;

    //f >> n;
    //f >> m;

    fscanf(f,"%d",&n);
    fscanf(f,"%d",&m);

    for (i = 0; i < m; i++)
        {
            fscanf(f,"%d",&x);
            fscanf(f,"%d",&y);

            v[x].push_back(y);
            v[y].push_back(x);
        }

    sursa = 1;

    if(sursa > n)
        return 0;

    while(vizitat[sursa] == 0)
    {

    vizitat[sursa] = 1;
    q.push(sursa);

    while (!q.empty())
        {
         nod = q.front();
         q.pop();

         for(i = 0; i < v[nod].size(); i++)
            if(vizitat[v[nod][i]] == 0)
                {
                    vizitat[v[nod][i]] = 1;
                    q.push(v[nod][i]);
                }
        }

    for(i = 1; i <= n; i++)
        if(vizitat[i] == 0)
            {sursa = i;
             k++;
            }
    cc++;
    }

    //g << cc;

    fprintf(g,"%d",cc);

    return 0;
}