#include <bits/stdc++.h>
#define int long long 
#define int128 __int128_t

using namespace std;

const int N = 3e5 + 10;
int n, m;
int128 al[N], ar[N], bl[N], br[N];
int128 s2[N], s1[N], s0[N];
int128 ans;

int128 calc(const int128 *a, const int128 *b) {
    vector<pair<int128, int>> c;
    for (int i = 1; i <= n; ++i) {
        c.emplace_back(a[i], 0);
    }
    for (int i = 1; i <= m; ++i) {
        c.emplace_back(b[i], 1);
    }
    sort(c.begin(), c.end());
    int128 sa0 = 0, sa1 = 0, sa2 = 0, sa3 = 0, sb0 = 0, sb1 = 0, sb2 = 0, sb3 = 0;
    int128 res = 0;
    for (int i = 0; i < n + m; ++i) {
        if (c[i].second == 0) {
            sa0 += 1;
            sa1 += c[i].first;
            sa2 += c[i].first * c[i].first;
            sa3 += c[i].first * c[i].first * c[i].first;
            res += -sb3 + 3 * sb2 * c[i].first - 3 * sb1 * c[i].first * c[i].first + sb0 * c[i].first * c[i].first * c[i].first;
        }
        else {
            sb0 += 1;
            sb1 += c[i].first;
            sb2 += c[i].first * c[i].first;
            sb3 += c[i].first * c[i].first * c[i].first;
            res += -sa3 + 3 * sa2 * c[i].first - 3 * sa1 * c[i].first * c[i].first + sa0 * c[i].first * c[i].first * c[i].first;
        }
    }
    return res;
}

int128 lsh[N];

int128 calc2(vector<pair<int128, int128>> q) {
    sort(q.begin(), q.end());
    int tot = 0;
    for (int i = 0; i < q.size(); ++i) {
        if (q[i].second == -1) {
            lsh[++tot] = q[i].first;
        }
        else {
            lsh[++tot] = q[i].second;
            lsh[++tot] = q[i].first;
        }
    }
    sort(lsh + 1, lsh + tot + 1);
    for (int i = 0; i <= tot; ++i) {
        s0[i] = s1[i] = s2[i] = 0;
    }
    for (int i = 0; i < q.size(); ++i) {
        if (q[i].second == -1) {
            int j = lower_bound(lsh + 1, lsh + tot + 1, q[i].first) - lsh;
            ++s0[j];
            s1[j] += q[i].first;
            s2[j] += q[i].first * q[i].first;
        }
    }
    for (int i = 1; i <= tot; ++i) {
        s0[i] += s0[i - 1];
        s1[i] += s1[i - 1];
        s2[i] += s2[i - 1];
    }
    int128 res = 0;
    for (int i = 0; i < q.size(); ++i) {
        if (q[i].second != -1) {
            int l = q[i].first, r = q[i].second;
            int il = lower_bound(lsh + 1, lsh + tot + 1, l) - lsh;
            int ir = lower_bound(lsh + 1, lsh + tot + 1, r) - lsh;
            res += r * r * s0[il] - l * l * s0[il] - 2 * s1[il] * r + 2 * s1[il] * l;
            res += (l * l + r * r) * (s0[ir] - s0[il]) + 2 * (s2[ir] - s2[il]) - 2 * (l + r) * (s1[ir] - s1[il]);
            res += (l * l - r * r) * (s0[tot] - s0[ir]) + 2 * (r - l) * (s1[tot] - s1[ir]);
        }
    }
    return res;
}

// int128 calc3()

signed main() {
    scanf("%lld%lld", &n, &m);
    for (int i = 1; i <= n; ++i) {
        int l, r;
        scanf("%lld%lld", &l, &r);
        al[i] = l, ar[i] = r;
    }
    // cerr << 1 << '\n';
    // return 0;
    for (int i = 1; i <= m; ++i) {
        int l, r;
        scanf("%lld%lld", &l, &r);
        bl[i] = l, br[i] = r;
    }
    int sa = 0, sb = 0;
    for (int i = 1; i <= n; ++i) {
        sa += ar[i] - al[i];
    }
    for (int i = 1; i <= m; ++i) {
        sb += br[i] - bl[i];
    }
    if (sa && sb) {
        ans += calc(al, br);
        ans -= calc(al, bl);
        ans += calc(ar, bl);
        ans -= calc(ar, br);
        // cerr << ans << '\n';
        // cout << (int) ans << '\n';
        
        // cerr << sa << ' ' << sb << '\n';
        long double Ans = (long double) ans;
        // cerr << Ans << '\n';
        Ans /= 6.0;
        Ans /= (long double) sa;
        Ans /= (long double) sb;
        printf("%.12Lf\n", Ans);
    }
    else if (sa && !sb) {
        vector<pair<int128, int128>> q;
        for (int i = 1; i <= n; ++i) {
            q.emplace_back(al[i], ar[i]);
        }
        for (int i = 1; i <= m; ++i) {
            q.emplace_back(bl[i], -1);
        }
        ans = calc2(q);
        long double Ans = (long double) ans;
        Ans /= 2.0;
        Ans /= (long double) sa;
        printf("%.12Lf\n", Ans);
    }
    else if (!sa && sb) {
        vector<pair<int128, int128>> q;
        for (int i = 1; i <= n; ++i) {
            q.emplace_back(al[i], -1);
        }
        for (int i = 1; i <= m; ++i) {
            q.emplace_back(bl[i], br[i]);
        }
        ans = calc2(q);
        long double Ans = (long double) ans;
        Ans /= 2.0;
        Ans /= (long double) sb;
        printf("%.12Lf\n", Ans);
    }
    else if (!sa && !sb) {
        vector<pair<int128, int>> q;
        for (int i = 1; i <= n; ++i) {
            q.emplace_back(al[i], 0);
        }
        for (int i = 1; i <= m; ++i) {
            q.emplace_back(bl[i], 1);
        }
        sort(q.begin(), q.end());
        int128 sa0 = 0, sa1 = 0, sb0 = 0, sb1 = 0;
        for (int i = 0; i < n + m; ++i) {
            // cerr << (int)q[i].first << '\n';
            if (q[i].second == 0) {
                ++sa0;
                sa1 += q[i].first;
                ans += sb0 * q[i].first - sb1;
            }
            if (q[i].second == 1) {
                ++sb0;
                sb1 += q[i].first;
                ans += sa0 * q[i].first - sa1;
                // cerr << (int)sa0 << ' ' << (int)sa1 << '\n';
            }
        }
        long double Ans = (long double) ans;
        Ans /= (long double) n;
        Ans /= (long double) m;
        printf("%.12Lf\n", Ans);
    }

    return 0;
}