#include <bits/stdc++.h>
using namespace std;

#define ll long long 
#define lll __int128
#define INF 0x3f3f3f3f
#define LNF 0x3f3f3f3f3f3f3f3fll
#define MOD 998244353
#define pii pair<int, int>
#define ld long double
#define fi first
#define se second
#define all(a) a.begin(), a.end()

#define N 20


int main() {
#ifdef TEST
    freopen("zz.in", "r+", stdin);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cout << setprecision(18);

    int n, m; cin >> n >> m;

    vector<pii> a(n), b(m);
    ll ca = 0, cb = 0;
    for (int i = 0; i < n; ++ i) cin >> a[i].fi >> a[i].se, ca += a[i].se - a[i].fi;
    for (int i = 0; i < m; ++ i) cin >> b[i].fi >> b[i].se, cb += b[i].se - b[i].fi;
    sort(all(a)), sort(all(b));

    auto pa = [&](pii x) {
        return ca ? (ld) (x.se - x.fi) / ca : (ld) 1 / n;
    };
    auto pb = [&](pii x) {
        return cb ? (ld) (x.se - x.fi) / cb : (ld) 1 / m;
    };
    auto w = [&](pii x) {
        return x.fi + (ld) (x.se - x.fi) / 2;
    };

    vector<ld> sp(m+1, 0), swp(m+1, 0);
    for (int i = 0; i < m; ++ i) {
        sp[i+1] = sp[i] + pb(b[i]);
        swp[i+1] = swp[i] + w(b[i]) * pb(b[i]);
    }

    ld res = 0;
    for (int i = 0, l = 0, r = 0; i < n; ++ i) {
        while (l < n && b[l].se < a[i].fi) ++ l;
        while (r < n && b[r].fi <= a[i].se) ++ r;
        
        res += (w(a[i]) * sp[l] - swp[l]) * pa(a[i]);
        res += ((swp[m] - swp[r]) - w(a[i]) * (sp[m] - sp[r])) * pa(a[i]);

        queue<pair<pii, pii>> cur;
        for (int j = l; j < r; ++ j) cur.emplace(a[i], b[j]);
        while (!cur.empty()) {
            auto [u, v] = cur.front(); cur.pop();
            if (u.fi == v.fi && u.se == v.se) {
                ld d = ca ? u.se - u.fi : 1;
                res += d * pa(u) * pb(v) / 3;
                continue;
            }
            if (u.fi < v.fi && v.se < u.se) {
                cur.emplace(pii(u.fi, v.fi), v);
                cur.emplace(pii(v.se, u.se), v);
                cur.emplace(v, v);
                continue;
            }
            if (v.fi < u.fi && v.se > u.fi) {
                cur.emplace(u, pii(v.fi, u.fi));
                cur.emplace(u, pii(u.fi, v.se));
                continue;
            }
            if (v.se > u.se && v.fi < u.se) {
                cur.emplace(u, pii(u.se, v.se));
                cur.emplace(u, pii(v.fi, u.se));
                continue;
            }
            res += abs(w(u) - w(v)) * pa(u) * pb(v); 
        }
    }

    cout << res << '\n';
}   

// = (p0w0/q0) * p1/q1 - (p1w1/q1) * (p0/q0)

// = (w0 - w1) * p1 * p0


// m = (r^2-l^2)/(2(r-l)), r-l=s

// (s1*(r0^2-l0^2)/2-s0*(r1^2-l1^2)) * s0 * s1 / q0 / q1




// y*1/m - x(r)/s

// = (sy-xrm)/sm

// a/s0 b/s1