#include <iostream>
#include <fstream>
#define MAX 100005
using namespace std;
ifstream f ("dfs.in");
ofstream g ("dfs.out");
int n,m,v[MAX],x,y,k,first[MAX],last[MAX];
struct
{
    int x,y,r;
}a[400005];
void comp(int x)
{
    int i,y;
    v[x]=1;
    i=first[x];
    //cout<<i<<'\n';
    while (i!=0)
    {
        y=a[i].y;
        if (v[y]==0) comp(y);
        i=a[i].r;
    }
}
int main()
{
    f>>n>>m;
    for (int i=1;i<=m;i++)
    {
        f>>a[2*i].x>>a[2*i].y;
        a[2*i+1].x=a[2*i].y;
        a[2*i+1].y=a[2*i].x;
        x=a[2*i].x;
        y=a[2*i].y;
        if (first[x]==0) first[x]=last[x]=2*i;
        else
        {
            a[last[x]].r=2*i;
            last[x]=2*i;
        }
        if (first[y]==0) first[y]=last[y]=2*i+1;
        else
        {
            a[last[y]].r=2*i+1;
            last[y]=2*i+1;
        }
    }
    for (int i=1;i<=n;i++)
    {
        if (v[i]==0)
        {
            comp(i);
            k++;
        }
    }
    g<<k;
    return 0;
}