#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;
        }
}
int con;


void DFS(int x)
{
//0- alb
//1- negru

culoare[x]=1;
    for(j=1;j<=a[x][0];j++)
            if(!culoare[a[x][j]])
                   {con++; DFS(a[x][j]);}

}



int main()
{
citire();

for(i=1;i<=n;i++)
            DFS(i);

cout<<con;







return 0;}