#include <iostream>
#include <fstream>
#include <vector>
#include <bitset>

using namespace std;

ifstream in("dfs.in");
ofstream out("dfs.out");

bitset<100005> U;
int n,m;
vector<int> L[100005];

void read(){
    in>>n>>m;
    for(int x,y,i=1;i<=n;i++){
        in>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
}
void dfs(int nod){
    U[nod]=1;
    for(auto x : L[nod]){
        if(!U[x])
            dfs(x);
    }
}
void solve(){
    int c=0;
    for(int i=1;i<=n;i++){
        if(!U[i]){
            dfs(i);
            c++;
        }
    }
    out<<c;
}
int main(){
    read();
    solve();
    return 0;
}