#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;
    vector<pii> s;
    for (int i = 0; i < n; ++ i) s.emplace_back(a[i].fi, 0), s.emplace_back(a[i].se, 0);
    for (int i = 0; i < m; ++ i) s.emplace_back(b[i].fi, 1), s.emplace_back(b[i].se, 1);
    sort(all(s));

    auto pa = [&](int len) {
        return ca ? 1.0L * len / ca : 1.0L / n;
    };
    auto pb = [&](int len) {
        return cb ? 1.0L * len / cb : 1.0L / m;
    };

    ld res = 0, sa = 0, sb = 0, spa = 0, spb = 0;
    int ia = 0, ib = 0;
    for (int i = 0; i < s.size() - 1; ++ i) {
        ia ^= s[i].se == 0;
        ib ^= s[i].se == 1;
        int len = s[i+1].fi - s[i].fi;
        ld mid = s[i].fi + (s[i+1].fi - s[i].fi) / 2.0L;

        if (ia && ib) res += 1.0L * len * pa(len) * pb(len) / 3.0L;
        if (ia) {
            res += (spb * mid - sb) * pa(len);
        }
        if (ib) {
            res += (spa * mid - sa) * pb(len);
        }
        if (ia) {
            spa += pa(len);
            sa += mid * pa(len);
        }
        if (ib) {
            spb += pb(len);
            sb += mid * pb(len);
        }
    }

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

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

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