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

typedef long long LL;

#define N 509

struct Node {
    int x1, y1, x2, y2;
} a[N];

int n, m, xx, yy;
map <int, int> X, Y;
int rx[N], ry[N];

int cx[N][N], cy[N][N];
int id[N][N];

struct Edge {
    int v; double w;
};
vector <Edge> E[N * N];

void add(int u, int v, double w) {
    E[u].push_back({v, w});
    E[v].push_back({u, w});
}

double dis[N * N];

priority_queue < pair<double, int>, vector < pair<double, int> >, greater< pair<double, int> > > q;
double dij(int sx, int sy, int ex, int ey) {
    int s = id[sx][sy], e = id[ex][ey];
    for (int i = 1; i <= m; i++) dis[i] = 1e10;
    dis[s] = 0;
    q.push({0., s});
    while (!q.empty()) {
        pair<double, int> u = q.top(); q.pop();
        if (dis[u.second] != u.first) continue;
        int x = u.second; double d = u.first;
        for (auto v : E[x]) {
            if (dis[v.v] > d + v.w) {
                dis[v.v] = d + v.w;
                q.push({dis[v.v], v.v});
            }
        }
    }
    return dis[e];
}

void work() {
    X.clear(); Y.clear();
    for (int i = 0; i <= xx; i++) {
        for (int j = 0; j <= yy; j++) {
            cx[i][j] = cy[i][j] = 0;
        }
    }

    xx = yy = 0;



    scanf("%d", &n);
    for (int i = 1; i <= n + 1; i++) {
        int x1, y1, x2, y2;
        scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
        X[x1] = 0;
        X[x2] = 0;
        Y[y1] = 0;
        Y[y2] = 0;
        a[i] = {x1, y1, x2, y2};
    }
    for (auto &i : X) rx[i.second = ++xx] = i.first;
    for (auto &i : Y) ry[i.second = ++yy] = i.first;
    
    for (int i = 1; i <= n; i++) {
        int x1, y1, x2, y2;
        x1 = X[a[i].x1];
        x2 = X[a[i].x2];
        y1 = Y[a[i].y1];
        y2 = Y[a[i].y2];
        for (int x = x1; x <= x2; x++) {
            for (int y = y1; y < y2; y++) {
                cx[x][y]++;
            }
        }
        for (int y = y1; y <= y2; y++) {
            for (int x = x1; x < x2; x++) {
                cy[x][y]++;
            }
        }
    }
    m = 0;
    for (int i = 1; i <= xx; i++) {
        for (int j = 1; j <= yy; j++) {
            id[i][j] = ++m;
        }
    }
    for (int i = 1; i <= m; i++) E[i].clear();
    for (int i = 1; i <= xx; i++) {
        for (int j = 1; j <= yy; j++) {
            if (i < xx) {
                add(id[i][j], id[i + 1][j], double(rx[i + 1] - rx[i]) / (cy[i][j] + 1));
            //    cerr << rx[i] << " " << ry[j] << " -> " << rx[i + 1] << " " << ry[j] << "  : " << double(rx[i + 1] - rx[i]) / (cy[i][j] + 1) << endl;
            }
            if (j < yy) {
                add(id[i][j], id[i][j + 1], double(ry[j + 1] - ry[j]) / (cx[i][j] + 1));
            //    cerr << rx[i] << " " << ry[j] << " -> " << rx[i] << " " << ry[j + 1] << "  : " << double(ry[i + 1] - ry[i]) / (cx[i][j] + 1) << endl;
            }
        }
    }
    printf("%.5lf\n", dij(X[a[n + 1].x1], Y[a[n + 1].y1], X[a[n + 1].x2], Y[a[n + 1].y2]));
}

int main() {
    int T;
    cin >> T;
    while (T--) work();


}