#include <cstdio>
#include<vector>
using namespace std;
vector<int> v[100010];
int n,m,i,viz[100010],x,y;
void DFS(int);
int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(;m;m--)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for(i=1;i<=n;i++)
    if(!viz[i])
    {
        m++;
        DFS(i);
    }
    printf("%d",m);
    return 0;
}
void DFS(int nod)
{
    viz[nod]=1;
    for(vector<int>::iterator it=v[nod].begin();it!=v[nod].end();it++)
        if(!viz[*it])
            DFS(*it);
}