#include<cstdio>
int ufs[100050];
int find(int x){
	if(x!=ufs[x])ufs[x]=find(ufs[x]);
	return ufs[x];
}
bool linked(int a,int b){
	return find(a)==find(b);
}
void link(int a,int b){
	ufs[find(a)]=find(b);
}
int main(){
	#define read
	#ifdef read
	freopen("explosion.in","r",stdin);
	freopen("explosion.out","w",stdout);
	#endif
	int tot = 0;
	int a,b;
	for(int i = 1;i<=100000;++i)ufs[i]=i;
	while(scanf("%d %d",&a,&b)==2){
		if(!linked(a,b))link(a,b);
		else tot++;
	}
	printf("%d",tot); 
	fclose(stdin);fclose(stdout);
	return 0;
}