#include<bits/stdc++.h>
using namespace std;
inline int read(){
	int w=0;
	char ch=getchar();
	while(ch<'0'||ch>'9'){
		ch=getchar();
	}
	while(ch>='0'&&ch<='9'){
		w=(w<<1)+(w<<3)+(ch-48);
		ch=getchar();
	}
	return w;
}
int fa[10005];
int find(int r){
	if(fa[r]==r) return r;
	fa[r]=find(fa[r]);
	return fa[r];
}
int solve(int z,int v){
	for(int i=1;i<=z;i++) fa[i]=i;
	for(int i=1;i<=v;i++){
		int a,b;
		a=read();b=read();
		if(a==b) continue;
		int x=find(a),y=find(b);
		if(x!=y) fa[x]=y;	
	}
	int u=find(1),ans=1;
	for(int i=2;i<=z;i++){
		int h=find(i);
		if(u==h) ans++;
	}
	return ans;
}
int main(){
	int n,m,p,q;
	n=read();m=read();
	p=read();q=read();
	cout<<min(solve(n,p),solve(m,q))<<endl;
	return 0;
}