#include<iostream>
#include<cstdio>
using namespace std;
int ans;
int f[50005],num[50005],bb;
int find(int a){
    if(f[a]==a){
        return a;
    }
    return f[a]=find(f[a]);
}
int main(){
    freopen("religion.in","r",stdin);
    freopen("religion.out","w",stdout);
    int n,m,x,y;
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        f[i]=i;
        num[i]=1;
    }
    for(int i=1;i<=m;i++){
        scanf("%d%d",&x,&y);
        if(find(y)==find(x)){
            continue;
        }
        num[find(y)]+=num[find(x)];
        num[find(x)]=0;
        f[find(x)]=find(y);
    }
    for(int i=1;i<=n;i++){
        if(num[i]!=0){
            ans++;
        }
    }
    cout<<ans;
    fclose(stdin);
    fclose(stdout);
    return 0;
}