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

using namespace std;
ifstream fin("dfs.in");
ofstream fout("dfs.out");
int n, m, i, j, c[100001],a, b, nr, x;
vector <int> v[100001];
queue <int> q;
int main()
{
    fin>>n>>m;
    for(i=1; i<=m; i++)
    {
        fin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for(i=1; i<=n; i++)
    {
        q.push(i);
        if(c[i]==0)
        {
            while(!q.empty())
            {
                x=q.front();
                for(auto j=v[x].begin(); j<v[x].end(); j++)
                {
                    if(c[*j]==0)
                    {
                        c[*j]=1;
                        q.push(*j);
                    }
                }
                q.pop();
            }
            c[i]=1;
            nr++;
        }
    }
    fout<<nr;
    return 0;
}