#include<stdio.h>
int a[100010],max=0;

void search(int x,int y)
{
int i;
for(i=1;i<=max;i++)
	if(a[i]==x)
		a[i]=y;
}

int main()
{
freopen("dfs.in","r",stdin);
freopen("dfs.out","w",stdout);
int n,k,i,no=0,x,y;
scanf("%d%d",&n,&k);
for(i=1;i<=n;i++)
	{a[i]=i;}
for(i=1;i<=k;i++)
	{
	scanf("%d%d",&x,&y);
	if(x<max)
		max=x;
	if(y>max)
		max=y;
	if(x<y)
		search(y,x);
	else
		search(x,y);
	}
for(i=1;i<=n;i++)
	if(a[i]==i)
		no++;
printf("%d",no);
return 0;
}