#include <iostream>
#include <fstream>
#include <cstdio>
using namespace std;

int v[100001],n,m,nr;

int main()
{int i,x,y;
ifstream f("dfs.in");
FILE *g;
g=fopen("dfs.out","w");
f>>n>>m;
for(i=1;i<=m; i++)
    {
    f>>x>>y;
    if(v[x]==0 && v[y]==0)
        {v[x]=v[y]=++nr;
        }
    else
        if(v[x]!=0)
            v[y]=v[x];
        else
            v[x]=v[y];
    }
for(i=1;i<=n; i++)
    if(v[i]==0)
        {v[i]=++nr;
        }

fprintf(g,"%d",nr);

return 0;
}