#include <cstdio>
#include <vector>

using namespace std;

vector<int> v[100010];
int vaz[200010],d[100010];

int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    int n,m,x,y,r=0;
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    x=0;y=0;
    for(int i=1;i<=n;i++)
    {
        if(vaz[i]==0)
        {
            vaz[i]=1;
            r++;
            d[0]=1;x=y+1;y=x;d[x]=i;
            while(d[0]>0)
            {
                for(int j=0;j<v[d[x]].size();j++)
                    if(vaz[v[d[x]][j]]==0)
                {
                    y++;
                    d[0]++;
                    d[y]=v[d[x]][j];
                    vaz[v[d[x]][j]]=1;
                }
                x++;d[0]--;
            }
        }
    }
    printf("%d",r);
    return 0;
}