#include <iostream>
#include <fstream>

using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
int Start[100005],T[2][200005],n,m,viz[100005],k;
void Citire()
{
    int i,j;
    f>>n>>m;
    while (f>>i>>j)
    {
        k++;
        T[0][k]=j;
        T[1][k]=Start[i];
        Start[i]=k;
        k++;
        T[0][k]=i;
        T[1][k]=Start[j];
        Start[j]=k;
    }
}
int dfs(int start)
{
    int contor=0,c;
    for(int i=1;i<=n;i++)
    {
        if(viz[i]==0)
            contor++;
        if(viz[i]==0)
        {
            c=Start[i];
            viz[i]=1;
            if(T[1][c]!=0)
                while(T[1][c]!=0)
                {
                    viz[T[0][c]]=1;
                    c=T[1][c];
                    viz[T[0][c]]=1;
                }
            else viz[T[0][c]]=1;
        }

    }
    return contor;
}
int main()
{
    Citire();
    g<<dfs(1);
}