#include<fstream>
#define dim 2009
using namespace std;
int n,a[dim][dim],viz[dim],m;
ofstream g("biconex.out");
ifstream f("biconex.in");
void citire()
{
    int i,j;
    f>>n>>m;
    for(int i=1;i<=m;i++)
    {
        f>>i>>j;
        a[i][j]=1;
        a[j][i]=1;
        a[i][i]=1;
        a[j][j]=1;
    }
}
void dfs(int vf)
{
    viz[vf]=1;
    for(int i=1;i<=a[vf][0];i++)
    if(!viz[i])
    dfs(a[vf][i]);
}
int main()
{
    int p=0;
    citire();
    for(int i=1;i<=n;i++)
    if(!viz[i])
    {
        dfs(i);
        p++;
    }
    g<<p/2<<"\n";
}