#include <cstdio>
#include<vector>
using namespace std;
vector<int> v[100010];
int n,m,x,y,i,viz[100010];
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 x)
{
    viz[x]=1;
    for(vector<int>::iterator it=v[x].begin();it!=v[x].end();it++)
    if(!viz[*it]) dfs(*it);
}