#include <fstream>
#include <vector>
using namespace std;
vector <int> v[50002];
vector <int>::iterator it;
ifstream f("dfs.in");
ofstream g("dfs.out");
int i,n,m,j,x,y,l;
void dfs(int i)
{
    v[i].pop_back();
    v[i].push_back(1);
    for (j=0;j<v[i].size();j++)
    {
        if (v[v[i][j]].back()==0)
        dfs(v[i][j]);
    }
}
int main()
{
    f>>n>>m;
    for (i=1;i<=m;i++)
    {
       f>>x>>y;

       if (x<y)v[x].push_back(y);
       else v[y].push_back(x);
    }
    for (i=1;i<=n;i++)
    v[i].push_back(0);
    for (i=1;i<=n;i++)
    if (v[i].back()==0)
    {
    l++;
    dfs(i);
    }
    g<<l;
    return 0;
}