#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;
}