#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
typedef long long ll;
typedef __int128 LL;
typedef pair<int,int> pii;
const int N=100005;
int n,m;
ll nn,mm;
LL ans;
pii a[N],b[N];
struct Data{
    ll P;LL E;
    Data operator + (const Data &n)const{
        return Data{P+n.P,E+n.E};
    }
    double operator - (const Data &n)const{
        return E*n.P-P*n.E;
    }
}sa,sb,Sa,Sb;
ll sqr(int k){
    return (ll)k*k;
}
LL cube(int k){
    return (LL)k*k*k;
}
LL calc(pii x,pii y){
    if ((!nn)&&(!mm))return 6LL*abs(x.fi-y.fi);
    if ((!nn)||(!mm)){
        if (!mm)swap(x,y);
        if (x.fi<y.fi)return (LL)3*(y.se-y.fi)*(0LL+y.fi+y.se-x.fi-x.fi);
        if (x.fi>y.se)return (LL)3*(y.se-y.fi)*(0LL+x.fi+x.fi-y.fi-y.se);
        return (LL)3*(sqr(x.fi-y.fi)+sqr(y.se-x.fi));
    }
    if (x.fi>y.fi)swap(x,y);
    if (x.se<y.fi)return (LL)3*(x.se-x.fi)*(y.se-y.fi)*(0LL+y.fi+y.se-x.fi-x.se);
    LL s=(LL)3*(y.fi-x.fi)*(y.se-y.fi)*(y.se-x.fi);
    x.fi=y.fi;
    if (x.se>y.se)swap(x,y);
    return s+2*cube(x.se-x.fi)+(LL)3*(x.se-x.fi)*(y.se-x.se)*(y.se-x.fi);
}
int main(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)scanf("%d%d",&a[i].fi,&a[i].se);
    for(int i=1;i<=m;i++)scanf("%d%d",&b[i].fi,&b[i].se);
    sort(a+1,a+n+1),sort(b+1,b+m+1);
    for(int i=1;i<=n;i++)nn+=a[i].se-a[i].fi;
    for(int i=1;i<=m;i++)mm+=b[i].se-b[i].fi;
    sa=sb=Sa=Sb=Data{0,0};
    for(int i=1,j=1;(i<=n)||(j<=m);){
        if ((i<=n)&&(j<=m))ans+=calc(a[i],b[j]);
        if ((i<=n)&&((j>m)||(a[i].se<b[j].se))){
            Data o=Data{(nn ? a[i].se-a[i].fi : 1),3*(sqr(a[i].se)-sqr(a[i].fi))};
            i++,ans+=o-sb,sb=sb+Sb,Sa=Sa+o,Sb=0;
        }
        else{
            Data o=Data{(mm ? b[j].se-b[j].fi : 1),3*(sqr(b[j].se)-sqr(b[j].fi))};
            j++,ans+=o-sa,sa=sa+Sa,Sb=Sb+o,Sa=0;
        }
    }
    printf("%.9f\n",ans/6.0/(nn ? nn : n)/(mm ? mm : m));
    return 0;
}

answer.code: In function ‘int main()’:
answer.code:55:47: error: no match for ‘operator=’ (operand types are ‘Data’ and ‘int’)
   55 |             i++,ans+=o-sb,sb=sb+Sb,Sa=Sa+o,Sb=0;
      |                                               ^
answer.code:13:8: note: candidate: ‘constexpr Data& Data::operator=(const Data&)’
   13 | struct Data{
      |        ^~~~
answer.code:13:8: note:   no known conversion for argument 1 from ‘int’ to ‘const Data&’
answer.code:13:8: note: candidate: ‘constexpr Data& Data::operator=(Data&&)’
answer.code:13:8: note:   no known conversion for argument 1 from ‘int’ to ‘Data&&’
answer.code:59:47: error: no match for ‘operator=’ (operand types are ‘Data’ and ‘int’)
   59 |             j++,ans+=o-sa,sa=sa+Sa,Sb=Sb+o,Sa=0;
      |                                               ^
answer.code:13:8: note: candidate: ‘constexpr Data& Data::operator=(const Data&)’
   13 | struct Data{
      |        ^~~~
answer.code:13:8: note:   no known conversion for argument 1 from ‘int’ to ‘const Data&’
answer.code:13:8: note: candidate: ‘constexpr Data& Data::operator=(Data&&)’
answer.code:13:8: note:   no known conversion for argument 1 from ‘int’ to ‘Data&&’
answer.code:44:10: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   44 |     scanf("%d%d",&n,&m);
      |     ~~~~~^~~~~~~~~~~~~~
answer.code:45:31: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   45 |     for(int i=1;i<=n;i++)scanf("%d%d",&a[i].fi,&a[i].se);
      |                          ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
answer.code:46:31: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   46 |     for(int i=1;i<=m;i++)scanf("%d%d",&b[i].fi,&b[i].se);
      |                          ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~