#include<bits/stdc++.h>
using namespace std;
ifstream F("dfs.in");
ofstream G("dfs.out");
int n,i,j,k;
vector<int> v[100001];
bool c[100001];
void A(int i)
{
    c[i]=1;
    for(auto j:v[i])
        if(!c[j])
            A(j);
}
int main()
{
    for(F>>n>>i;F>>i>>j;v[i].push_back(j),v[j].push_back(i));
    for(i=1;i<=n;!c[i]?A(i),++k:0,++i);
    return G<<k,0;
}