#include<fstream>
#include<vector>
using namespace std;
#define N 100001
ifstream F("dfs.in");
ofstream G("dfs.out");
vector<int> v[N];
int n,m,c,i;
bool u[N];
void D(int i)
{
    int j,k;
	for(u[i]=1,k=v[i].size(),j=0;j<k;++j)
        if(!u[v[i][j]])
            D(v[i][j]);
}
int main()
{
    F>>n>>m;
    while(m--)
		F>>i>>c,v[i].push_back(c),v[c].push_back(i);
	for(c=0,i=1;i<=n;++i)
        if(!u[i])
            ++c,D(i);
	G<<c;
	return 0;
}