#include<iostream>
#include<cstdio>
using namespace std;
int n,m,f[50010],b[50010],ans;
int find(int x)
{
    if(f[x]==x) return x;
    else return f[x]=find(f[x]);
}
void merge(int x,int y)
{
    int fx=find(x);
    int fy=find(y);
    if(fx!=fy)
    {
        f[fx]=fy;
    }
}
int main()
{
    freopen("religion.in","r",stdin);
    freopen("religion.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
    {
        f[i]=i;
    }
    for(int i=1;i<=m;i++)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        merge(a,b);
    }
    for(int i=1;i<=n;i++) find(i);
    for(int i=1;i<=n;i++)
    {
        if(b[f[i]]==0) ans++;
        b[f[i]]=1;
    }
    printf("%d",ans);
    return 0;
}