#include <fstream>
#include <algorithm>
#include <queue>
#define NMAX 100005

using namespace std;

ifstream fin("dfs.in");
ofstream fout("dfs.out");
int n, m, viz[NMAX], p,i,x,y,a[3][1000010],k,start[100010],j,conex;

queue <int> q;

void dfs(int nod)
{
    int p, y;
    viz[nod] = 1;
    x=start[nod];

    while(x!=0)
    {
        if(viz[a[0][x]]==0)
        {
            q.push(a[0][x]);
        }
        x=a[1][x];
    }

    while(! q.empty())
    {
        p = q.front();
        q.pop();
        if(viz[p]==0)
            dfs(p);

    }
}

int main()
{
    fin >> n >> m;
    k=0;
    for (i = 1; i <= m; i++)
    {
        fin >> x >> y;
        k++;
        a[0][k]=y;
        a[1][k]=start[x];
        start[x]=k;
        k++;
        a[0][k]=x;
        a[1][k]=start[y];
        start[y]=k;
    }

    for(i=1; i<=n; i++)
    {
        if(viz[i]==0)
        {
            dfs(i);
            conex++;
        }
    }
    fout<<conex;
}