#include<stdio.h>
#include<vector>
using namespace std;
int N,M,x,y,v[100100],rez;
vector <int> a[100100];

void DFS(int i)
{
    v[i]=1;
    int x=a[i].size();
    for(int j=0;j<x;++j)
        if(v[a[i][j]]==0)
            DFS(a[i][j]);
}

int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    scanf("%d%d",&N,&M);

    for(int i=1;i<=M;++i)
    {
        scanf("%d%d",&x,&y);
        a[x].push_back(y);
        a[y].push_back(x);
    }

    for(int i=1;i<=N;++i)
    {
        if(v[i]!=1)
        {
            DFS(i);
            ++rez;
        }
    }

    printf("%d",rez);

    return 0;
}