#include<stdio.h>   
#define dim 100001
int comp[dim];   
int main()   
{   
FILE *f=fopen("dfs.in","r");   
FILE *g=fopen("dfs.out","w");   
int n,m;   
int x,y,j,cont=0,i,minim;   
  
fscanf(f,"%d",&n);   
fscanf(f,"%d",&m);   
for(i=1;i<=n;i++) comp[i]=i;   
cont=n;   
for(i=1;i<=m;i++)   
 {fscanf(f,"%d",&x);   
  fscanf(f,"%d",&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;   
}