// clang-format off
#include<bits/stdc++.h>
#define pb push_back
#define st first
#define nd second
#define bit(s,x) (((s)>>(x))&1)
#define ctz(s) __builtin_popcount(s)
using namespace std;
typedef long long ll; 
typedef unsigned long long ull; 
//typedef __int128 i128; 
typedef long double ld;
typedef pair<int,int> pii; typedef pair<ll,int> pli; typedef pair<ll,ll> pll; typedef pair<int,ll> pil;
inline ll read(){
	ll x=0,f=1,c=getchar();
	while(c<'0'||c>'9')f=(c=='-'?-1:1),c=getchar();
	while(c>='0'&&c<='9')x=(x<<1)+(x<<3)+(c^48),c=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'); }
// remember to change!!!
const int mod=998244353;
inline void plust(int &x,int y,int p=mod){x=x+y<p?x+y:x+y-p;}
inline void mul(int &x,int y,int p=mod){x=1ll*x*y%p;}
inline int fp(int x,ll p=mod-2,int m=mod,int res=1){
	for(;p;p>>=1){if(p&1)mul(res,x,m);mul(x,x,m);}
	return res;
}
const int N=1e5+10;
const int INF=0x3fffffff;
// clang-format on
int n,m;
pll a[N],b[N];
double s[N],sp[N];
double s1=0,s2=0;
inline double P(ll a,ll b){
	if(a==0 && b==0)return 1.0;
	return 1.0*a/b;
}
inline double f(ll l1,ll r1,ll l2,ll r2){
	return abs(r2+l2-l1-r1)*0.5*P(r2-l2,s2)*P(r1-l1,s1);
}
inline double calc(int i,int j){
	
	double res = 0;
	if(a[i].st < b[j].st){
		if(a[i].nd < b[j].nd){
			assert(a[i].st <= b[j].st && b[j].st <= a[i].nd && a[i].nd <= b[j].nd);
			res += f(a[i].st,b[j].st,b[j].st,b[j].nd);
			res += f(b[j].st,a[i].nd,a[i].nd,b[j].nd);
			res += 1.0*(a[i].nd-b[j].st)/3*P(a[i].nd-b[j].st,s2)*P(a[i].nd-b[j].st,s1);
		}
		else{
			assert(a[i].st <= b[j].st && b[j].st <= b[j].nd && b[j].nd <= a[i].nd);
			res += f(a[i].st,b[j].st,b[j].st,b[j].nd);
			res += f(b[j].nd,a[i].nd,b[j].st,b[j].nd);
			res += 1.0*(b[j].nd-b[j].st)/3*P(b[j].nd-b[j].st,s2)*P(b[j].nd-b[j].st,s1);
		}
	}
	else{
		if(b[j].nd < a[i].nd){
			assert(b[j].st <= a[i].st && a[i].st <= b[j].nd && b[j].nd <= a[i].nd);
			res += f(b[j].nd,a[i].nd,b[j].st,b[j].nd);
			res += f(a[i].st,b[j].nd,b[j].st,a[i].st);
			res += 1.0*(b[j].nd-a[i].st)/3*P(b[j].nd-a[i].st,s1)*P(b[j].nd-a[i].st,s2);
		}
		else{
			assert(b[j].st <= a[i].st && a[i].st <= a[i].nd && a[i].nd <= b[j].nd);
			res += f(a[i].st,a[i].nd,b[j].st,a[i].st);
			res += f(a[i].st,a[i].nd,a[i].nd,b[j].nd);
			res += 1.0*(a[i].nd-a[i].st)/3*P(a[i].nd-a[i].st,s1)*P(a[i].nd-a[i].st,s2);
		}
	}
	return res;
}
int main() {
    //freopen("data.in", "r", stdin);
    // freopen(".in","r",stdin);
    // freopen("myans.out","w",stdout);
	n=read(),m=read();
	for(int i=1;i<=n;++i)a[i].st=read(),a[i].nd=read(),s1+=a[i].nd-a[i].st;
	for(int i=1;i<=m;++i)b[i].st=read(),b[i].nd=read(),s2+=b[i].nd-b[i].st;
	sort(a+1,a+n+1),sort(b+1,b+m+1);
	for(int i=1;i<=n;++i)s[i]=s[i-1] + (a[i].st+a[i].nd)*0.5*P(a[i].nd-a[i].st,s1);
	for(int i=1;i<=n;++i)sp[i]=sp[i-1] + P(a[i].nd-a[i].st,s1);
	double ans=0;
	for(int i=1,lst1=1,lst2=1;i<=m;++i){
		while(lst1<=n && a[lst1].nd < b[i].st)++lst1;
		while(lst2<=n && a[lst2].st < b[i].nd)++lst2;
		double p2 = P(b[i].nd-b[i].st,s2),res=0;
		assert(lst1 <= 1 || a[lst1-1].nd <= b[i].st);
		assert(lst2 > n||a[lst2].st >= b[i].nd);
		if(lst1 > 1) res += (sp[lst1-1]*(b[i].st+b[i].nd)*0.5 - s[lst1-1])*p2;
		if(lst2 <= n) res += (s[n] - s[lst2-1] - (sp[n] - sp[lst2-1])*(b[i].st+b[i].nd)*0.5)*p2;
		for(int j=lst1;j<lst2;++j)res += calc(j,i);
		ans += res;
	}
	printf("%.15lf",ans);
    return 0;
}