#include <cstdio>
#include <vector>
using namespace std;

vector<int> Adj[1000005];

int n,m;
bool viz[100005];
int l=0;

void citire()
{
    scanf("%d %d",&n,&m);
    int a,b;
    for(int i=0;i<m;i++)
    {
    scanf("%d %d",&a,&b);
    Adj[a].push_back(b);
    Adj[b].push_back(a);
    }
}


void parc(int nr)
{
    if(viz[nr]==0)
        viz[nr]=1;
    for(auto it:Adj[nr])
    {
        if(viz[it]==0)
            parc(it);
    }
}

void DFS()
{
    for(int i=1;i<=n;i++)
    {
    if(viz[i]==0)
        {
        l++;
        parc(i);
        }
    else
        continue;
    }
}

int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    citire();
    DFS();
    printf("%d",l);
    return 0;
}