#include<stdio.h>
#define dim 100001

FILE *f=fopen("dfs.in","r");
FILE *g=fopen("dfs.out","w");
int comp[dim],aux[dim];

int main()
{

int n,m;
int x,y,j,cont=0,i,minim;
  
fscanf(f,"%d %d",&n,&m);

for(i=1;i<=n;i++) comp[i]=i;

cont=n;
for(i=1;i<=m;i++)
 {fscanf(f,"%d %d",&x,&y);
  if(comp[x]<comp[y])   
   {minim=comp[y];   
    for(j=1;j<=n;j++)   
     if(comp[j]==minim) comp[j]=comp[x];   
    cont--;   
   }   
   else if(comp[x]>comp[y])   
      {minim=comp[x];   
       for(j=1;j<=n;j++)   
    if(comp[j]==minim) comp[j]=comp[y];   
       cont--;   
      }   
 }   

fprintf(g,"%d",cont);
fprintf(g,"\n");

return 0;   
}