#include <fstream>
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
int n,m,i,j,x,y,a[10001][10001],nr;bool sel[100001];
void load()
{
    f>>n>>m;
    for (i=1; i<=n; i++)
        for (j=1; j<=n; j++) a[i][j]=0;
    for (i=1; i<=m; i++)
    {
        f>>x>>y;
        a[x][y]=1;
        a[y][x]=1;
    }
}
void df(int x)
{int i;
sel[x]=true;
for (i=1;i<=n;i++)
if (a[x][i] && !sel[i]) nr++,df(i);
}
int main()
{
    load();
    for (int i=1;i<=n;i++) if (!sel[i]) df(i);
    g<<nr;
    return 0;
}