#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define pii pair<ll,ll>
#define rep(i,a,b) for(ll i=(a);i<=(b);++i)
#define per(i,a,b) for(ll i=(a);i>=(b);--i)
using namespace std;
bool Mbe;
inline ll read(){
	ll x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-f;ch=getchar();}
	while(ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
	return x*f;
}
inline void write(ll x){
	if(x<0)putchar('-'),x=-x;
	if(x>9)write(x/10);
	putchar(x%10+'0');
}
const ll N=4e5+9;
ll n,m,suma,sumb,tot;
struct Seg{
	ll l,r;
}a[N],b[N];
struct Node{
	ll p,t;
}c[N];
ld coefa(ll len){
	if(suma==0)return 1./n;
	return len*1./suma;
}
ld coefb(ll len){
	if(sumb==0)return 1./m;
	return len*1./sumb;
}
bool Med;
int main(){
	cerr<<fabs(&Med-&Mbe)/1048576.0<<"MB\n";
	n=read(),m=read();
	rep(i,1,n)a[i].l=read(),a[i].r=read();
	rep(i,1,m)b[i].l=read(),b[i].r=read();
	rep(i,1,n)suma+=a[i].r-a[i].l;
	rep(i,1,m)sumb+=b[i].r-b[i].l;
	rep(i,1,n)c[++tot]=(Node){a[i].l,0},c[++tot]=(Node){a[i].r,0};
	rep(i,1,m)c[++tot]=(Node){b[i].l,1},c[++tot]=(Node){b[i].r,1};
	sort(c+1,c+tot+1,[&](Node a,Node b){
		return a.p<b.p||(a.p==b.p&&a.t<b.t);
	});
	ld ans=0,pa=0,sma=0,pb=0,smb=0;
	ll fa=0,fb=0;
	rep(i,1,tot-1){
		if(!c[i].t)fa^=1;
		else fb^=1;
		ll len=c[i+1].p-c[i].p;
		ld mid=(c[i].p+c[i+1].p)/2.;
		if(fa&&fb)ans+=len*coefa(len)*coefb(len)/3.0;
		if(fa)ans+=(mid*pb-smb)*coefa(len);
		if(fb)ans+=(mid*pa-sma)*coefb(len);
		if(fa)pa+=coefa(len),sma+=mid*coefa(len);
		if(fb)pb+=coefb(len),smb+=mid*coefb(len);
	}
	cout<<fixed<<setprecision(12)<<ans;
	return 0;
}