#include<iostream>
#include<fstream>

#define IMAX 200000
//condition ? value if true : value if false


using namespace std;

ifstream f ("dfs.in");
ofstream o ("dfs.out");




int n,m,i,j, *a[IMAX],culoare[IMAX];
//int drum[IMAX];

void citire()
{
    f>>n>>m;
    int x,y;

    for(i=1;i<=n;i++)
        {
            a[i]=(int *)realloc(a[i],sizeof(int));
            a[i][0]=0;
        }

    for(i=1;i<=m;i++)
        {
            f>>x>>y;
            a[x][0]++;
            a[x]=(int *)realloc(a[x],(a[x][0]+1)*sizeof(int));
            a[x][a[x][0]]=y;
            a[y][0]++;
            a[y]=(int *)realloc(a[y],(a[y][0]+1)*sizeof(int));
            a[y][a[y][0]]=x;

        }
}
int con;

void viz(int x)
{
    culoare[x]=2;
    int k;
    for(k=1;k<=a[x][0];k++)
        if(!culoare[a[x][k]])
             {con++;viz(a[x][k]);}
   culoare[x]=1;
}


void DFS()
{

for(i=1;i<=n;i++)
    for(j=1;j<=a[i][0];j++)
        if(!culoare[a[i][j]])
                viz(a[i][j]);



}



int main()
{
citire();
DFS();
//viz(3);

o<<con;







return 0;}