#include <iostream>
#include <stdio.h>
#include <list>

int n, m, viz[100005], cnt;
using namespace std;

void DFS(list<int> x){
    for (std::list<int>::iterator it=x.begin(); it != x.end(); ++it)
       if(viz[*it]!=1) viz[*it]=1;
}


int main()
{
    FILE *f1,*f2;
    f1=fopen("dfs.in","r");
    f2=fopen("dfs.out","w");
    fscanf(f1,"%d %d",&n, &m);
    list<int> v[n+1];
    int i,x,y;
    for (i=0;i<m;i++){
        fscanf(f1,"%d %d",&x, &y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for (i=1;i<=n;i++){
        if(viz[i]!=1)
        {
            cnt++;
            viz[i]=1;
            DFS(v[i]);
        }
    }
    fprintf(f2,"%d",cnt);
    fclose(f1);
    fclose(f2);
    return 0;
}