学步园

#include<iostream>
#include<cstdio>
#define inf 0x7fffffff
using namespace std;
inline int read(){
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
int n,m,k,ans,a[2000001],b[2000001],fa[1000001];
inline int find(int x){
	return fa[x]==x?x:fa[x]=find(fa[x]);
}
int main(){
	n=read();m=read();k=read();
	for(int i=1;i<=n;++i)
		fa[i]=i;
	for(int i=1;i<=m;++i){
		a[i]=read();
		b[i]=read();
		if(a[i]>k&&b[i]>k){
			int p=find(a[i]),q=find(b[i]);
			if(p!=q)fa[p]=q;
		}
	}
	for(int i=1;i<=m;++i){
		if(a[i]<=k||b[i]<=k){
			int p=find(a[i]),q=find(b[i]);
			if(p!=q)fa[p]=q;
			else ++ans;
		}
	}	
	printf("%d",ans);
	return 0;
}