#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("dfs.in");
ofstream fout("dfs.out");
int main() 
{
   int n,k,i,x,y,j,nr,m=0 ,v[100001][100001],a[100001]={0};
   fin>>n>>k;
   for(i=1;i<=k;i++){
     fin>>x>>y;
     v[x][y]=v[y][x]=1;
   }
   for(i=1;i<=n;i++){
     nr=0 ;
     for(j=1;j<=n;j++){
       if(v[i][j]==1  && a[j]==0) {
         nr++; a[j]=1;
         v[i][j]=v[j][i]=0;
     }
    
   }
   if(nr>0) m++;
   if(a[i]==0 && nr==0) m++;
}
fout<<m;
}